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Activity theory, cognitive ergonomics and distributed cognition: three views of a transport company
Int. J. Human-Computer Studies (2000) 53, 5}33 doi:10.1006/ijhc.2000.0378 Available online at http://www.idealibrary.com on
Activity theory, cognitive ergonomics and distributed cognition: three views of a transport company FRANhOISE DECORTIS Work Psychology Department, FNRS University of Lie% ge, FAPSE B32, 5. Bd. du Rectorat, 4000 Lie% ge, Belgium. email: [email protected]; [email protected] SAMUEL NOIRFALISE- AND BERTHE SAUDELLIJoint Research Centre Ispra, VA21020, Italy
Activity theory, cognitive ergonomics and distributed cognition are three theoretical frameworks used to understand cooperative work settings. In the past, each has used case studies to describe and defend its point of view. However, comparisons are made di$cult by the fact that these studies are usually based on di!erent work settings. This paper describes the application of each framework to exactly the same setting. We believe our approach shows the features that are emphasized and those that are ignored in each framework, enabling us to di!erentiate their relevant questions. We discuss the e!ects of a theoretical "lter on understanding the work setting, the di!erences in the concept of activity, the tools and interactions between humans and tools, the concept of representation, and we look at how a plurality of viewpoints may broaden any interpretation. 2000 Academic Press
1. Introduction An example may be worth a thousand lengthy explanations. Activity theory, cognitive ergonomics and distributed cognition are the three theoretical frameworks used to understand cooperative work settings. In the past, each has used case studies to describe and defend its point of view. However, comparisons are made di$cult by the fact that each study used di!erent work settings. This paper applies each framework to exactly the same setting. We believe this approach highlights the features that are emphasized and those that are ignored, enabling us to di!erentiate the relevant questions posed by each theory. A working environment cannot be described independently of its theoretical framework and the conditions of its observation. How do these theoretical frameworks in#uence our interpretation of the facts &&Why are we using this type of approach'' As Patel and Groen (1993) suggested &&it may be illogical to compare apples and oranges, but it is possible to put them in the same basket. Nevertheless, it is incorrect to conclude that a theoretical framework is superior to another.'' -Now at Laboratorio Multimediale, Universita di Siena, 6 Via dei Termini, Siena, Italy.
1071-5819/00/070005#29 $35.00/0
2000 Academic Press
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It is not our intention to claim superiority for any particular framework. Our approach is primarily heuristic and hermeneutic. Its objective is to successfully handle multiple viewpoints and to determine the analytical pro"le of each viewpoint. This approach avoids what Laplantine (1996) calls the &&ontological illusion'' of unity, identity, stability and persistence of meaning. Using a single viewpoint can give the mistaken impression that it is the best viewpoint. Examining exactly the same situation from various viewpoints necessarily broadens any interpretation. One of our objectives is to understand di!erences and similarities of viewpoints, while taking into account the ontological, genetic and functional aspects of the object being analysed. Another two-part objective is (1) to understand the prominent features of each theory and then to look at the interpretations they generate in analysing work, and (2) to demonstrate the properties of work situations and activities that these frameworks enable us to perceive. We must make it clear that our aim is to contribute to the understanding of theoretical and methodological di!erences in order to help researchers make explicit and appropriate choices for their particular aim. Of course, this does not imply that work analysis is too narrowly focused unless all of these techniques are used, but rather that each produces one explicit interpretation for one work situation, and that this interpretation is one of many possible viewpoints. We picked these three frameworks because each can be used to analyse cooperative activities, even if that is not their only application. We could argue that they have di!erent epistemological orientations. Broadly speaking, distributed cognition has its roots in anthropology, while cognitive ergonomics and activity theory are derived from psychology, with cybernetic and anthropological in#uences present in cognitive ergonomics. Nevertheless, each of these frameworks analyses cognition in real settings, and rejects the conventional symbolic approach where factors are abstracted and studied out of context. Lave (1988) and Star (1996) showed that cognition observed in everyday practice is distributed and &&stretched over''. Activity theory, distributed cognition and cognitive ergonomics share a fundamental indeterminism. All are interested in the &&mysteries'' of workplaces and organizations (Star, 1996) as pathways of information, in distributed access of information (Hutchins & Klausen, 1996) and in regulation loops (Pavard, 1991). We have no pretensions of presenting an exhaustive description of these three complex frameworks. It would be a di$cult challenge to cover any one of them in a su$ciently comprehensive manner. Di!erent if not competing versions of activity theory are widely accepted, and some concepts like unity of consciousness and activity, object-orientedness, internalization}externalization will not be dealt with. The same is true for distributed cognition and cognitive ergonomics. A certain number of choices are made in terms of discriminative concepts. Among these, activity theory emphasizes objects, tools and activity, and a variety of viewpoints that actors have of their subject. Cognitive ergonomics more strongly emphasizes the distinctions between macro and micro analyses of the work situation and between the prescribed task and the activity actually carried out. A major distinguishing characteristic of distributed cognition is its focus on &&representational artefacts'' and the manner in which information is processed by the system (information path and transformation).
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We must caution the reader on two other points. The "rst involves the evolving nature of each of these frameworks, and the fact that we are looking at a single static moment in their existence, namely &&when'' we describe them. However, a framework is constantly faced with new questions and new work situations, and that means the de"nitions of concepts and their relationships constantly develop within these frameworks. It is possible that our view corresponds to speci"c moments in their development. The second point is that we have made a heterogeneous selection. The defenders of cognitive ergonomics insist that it is more a discipline or a "eld of study than a theoretical framework, and that this "eld may itself call upon concepts from activity theory and distributed cognition. This heterogeneity may also bias a comparative approach and lead us to some redundancy when we cover speci"c points. This article aims to present the work situation and the discussion around three main points of the activity, namely tools, interactions between humans and tools, and representations.
2. Methodological issues The comparison of these three approaches to the same work setting obviously has some limits. Any description involves building and reorganizing data. Laplantine (1996) posits that description is writing according to a model, which in turn means building, cutting up and analysing any reality in order to understand it. We do not invent the social processes and events as we witness and record. It is even a mistake to think that we render a faithful copy. We begin to restructure reality as soon as we do "eldwork. Notes or "lms are inevitably a selection of facts from a particular point of view. This means that the best "eldwork and subsequent analysis usually betrays the observer's analytical background, particularly in cognitive science. How do conditions of observation in#uence interpretations of facts'' Here we started from a preliminary report of a study performed on the same site using a cognitive ergonomics perspective (Rognin and Derwa, 1996). The study was conducted in an international transport company (BTK in Belgium), and was part of a larger project aimed at analysing user requirements of various transport companies in Germany, Belgium and Greece. We made observations at di!erent times. First we focused on production, IT and dispatch personnel. This initial contact brought up many questions. Each of us selected and analysed the dispatching work according to di!erent frameworks. We worked separately, taking notes and checking our observations against the concepts of each framework. Then we pooled our individual work and discussed di!erences, similarities and the unique aspects of each approach. Several months later, we made a second set of observations to "ll out our previous description. This work was done in a period of one week. We followed the dispatchers through their workday, making and subsequently transcribing video recordings. The last point that we would like to mention is that we have more extensive experience in using cognitive ergonomics than the other two frameworks. This means that we may have made incomplete or imprecise interpretations of the facts, particularly concerning activity theory and distributed cognition.
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In the following, we begin by presenting the general aspects of the work environment, and we then attempt to demonstrate the concepts that each of these frameworks o!ers for analysing the work situation at BTK.
3. The BTK working environment BTK is an international transport company with several o$ces in Europe. BTK was formed in 1946, and has concentrated on general dispatch work since 1991. The Grace Hollogne o$ce employs 22 people: 10 in the operations department, 8 in the billing department, 2 IT specialists, 1 "nancial manager and the general manager. BTK began dispatching for a paper factory. Since 1991, carriers and logistics personnel have been added to the payroll. About 280 orders are processed each day, which averages out to 20 orders per dispatcher. BTK receives transport orders from customers and subcontracts them to carriers. This is called &&freightage'', and is a speci"c activity in the transport sector. BTK's freightage activity is handled by dispatchers who match customer orders to available resources (drivers and trucks). Independently of any theoretical framework, the dispatchers' work can be described as making the best match between driver and transport order. Dispatchers minimize travel by empty trucks so as to reduce costs, provide the best prices for customers and achieve the greatest pro"ts for the company. This means the dispatcher plans return trips for each truck and driver. If a truck loads in Liege and unloads in Paris, the dispatcher has to "nd a return trip from near Paris to Liege, perhaps via a third stop. This level of planning requires cooperation between the dispatchers. Drivers may be switched from one dispatcher to another to achieve the most e$cient returns or overall routing. All dispatchers have to keep an eye and an ear on every other dispatcher's needs and available resources. The dispatching room (Figure 1) is designed for teamwork. There are seven dispatchers working on truck dispatching, plus two dispatchers responsible for multimodal transport (train/river/sea-container freightage). There are no walls in the dispatching room, and the dispatchers are seated face-to-face. The &&use space'' is organized according to the speci"c needs of the nine dispatchers. They have two telephones, a computer, some paper tables for planning, writing paper, notebooks and maps. The dispatchers are positioned for easy verbal communication. This corresponds with what the operational head of the dispatch room told us: &&a primary principle of this job is being able to listen peripherally.''
The room is designed so that everyone can observe everyone else: at the telephone, entering data into the computer or consulting planning tables. Each member of the group seems to concentrate on his or her task within the respective workspace. In fact, they often exchange information and help one another. An on-line computerized system was installed for real-time information processing and easier communication between dispatchers and the billing department. This information processing system is made up of the following components: the hardware consists of Network Novel, Intra net 4.11, Jet fax (and dedicated PC), PCs, printers; the software consists of an in-house program called Trans-BTK, in addition to conventional programs.
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FIGURE 1. The dispatching room con"guration (D1, dispatcher responsible for outward transports, D2 } D3, dispatchers responsible for return transports, D4, dispatcher responsible for the pallets management, D5, dispatcher responsible for transport from and to Germany, D6, dispatcher responsible for the transports from and to Benelux, D7, dispatcher responsible for the grouping of loads, D8}D9, dispatchers responsible for the multimodal transports).
We begin by describing activity theory's viewpoint on the BTK, then Cognitive Ergonomics' viewpoint and "nally Distributed Cognition's viewpoint.
4. BTK viewed by activity theory Activity theory is a psychological framework originated in Russia and has been developed there and elsewhere over the last 70 years. It has been broadly used more recently in western countries. The unit of reference for activity theory is the &&activity''. Each component of the work setting is explained with reference to the activity or context in which it occurs: &&actions are always situated in a context and are impossible to understand without that context'' (Kuutti, 1996)
The solution o!ered by activity theory is that a minimal meaningful context for individual actions must be included in the basic unit of analysis. Therefore, each action has to be analysed in the activity context in which it occurs. In the BTK o$ce, we look at dispatchers' actions and analyse them in the context of the transport activity. Of interest to us for the purpose of our analysis was the historical, dialectical and hermeneutical viewpoints that form part of activity theory. It is considered historical
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because it looks at the background and developmental aspects of the activity. Activity is studied within the context of ongoing changes. Human practices are seen as a developmental process in which individual and social factors are interlinked. Activity theory can also be considered as dialectical because the analysis aims &&to understand the competing forces at work in relations between the development of the individual and the society in which the individual exists. The features of the individual are explained as outgrowths of basic social forces'' (Bannon and Bodker, 1991).
Contradictions within the activity and with social forces are then seen as the origin of any change. Finally, activity theory can be hermeneutic because it provides an interpretative view of the work setting. It interprets di!erences between the views of the di!erent actors in the work setting as factors of contradiction and incompatibility between di!erent viewpoints that will create pressure for change (EngestroK m, 1993). 4.1. ACTIVITY LEVELS
Leontiev (1974) distinguishes three levels in every human activity: activity, action and operation. Kaptelinin, Kuutti and Bannon (1995) describe action as the central level in the breakdown of activity. Each action is oriented towards a goal. Each goal is functionally subordinated to other goals, up through the hierarchy of goals to the top-level goal, which is not subordinated to any other goal. This top-level goal is the object of the activity. If we move down the hierarchy of actions we might cross the border between conscious and automatic processes. When the individual is no longer aware of his/her behaviour, that behaviour fully depends on environmental conditions, and is de"ned as an operation. This means that activities are made up of actions or chains of actions, which are in turn made up of operations. In our application, the dispatchers' task is accomplished by a set of actions. Each action aims to achieve speci"c goals, for example: gathering needed information concerning an order, "nding the best truck to perform the transport, obtaining the driver's
FIGURE 2. Levels of activity (from Kuutti, 1996).
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agreement or entering the sold order in Trans-BTK. All of these actions are subordinated to the overriding top-level goal of dispatching, i.e. best match of driver trip with customer order. This goal is the object of the activity, and gives meaning to all related actions.
4.2. THE STRUCTURE OF ACTIVITY
EngestroK m (1990) proposes a schematic view of activity involving mediation. &&In the model, the subject refers to the individual or subgroup whose agency is chosen as the point of view in the analysis. The object refers to the &raw material' or &problem space' at which the activity is directed, and which is moulded or transformed into outcomes with the help of physical and symbolic, external and internal tools (mediating instruments and signs). The community is composed of multiple individuals and/or subgroups who share the same general objective. The division of labour refers to both the horizontal division of tasks between the members of the community and to the vertical division of power and status. Finally, the rules refer to the explicit and implicit regulations, norms and conventions that constrain actions and interactions within the activity system.'' (EngestroK m, 1990).
The activity of the subject towards the object is mediated by tools. This means that tools shape the way the activity is performed, and are themselves changed by the activity. In the same way, rules shape the relations between subject and community and are modi"ed by these interactions. Finally, the division of labour shapes the way the di!erent actors of the community take part in the transformation process, and is itself modi"ed by the activity.
FIGURE 3. The structure of the activity, the viewpoint of the entire team of dispatchers (adapted from Engestrom, 1993).
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4.3. VIEWPOINT VARIETY
Activity theory's value as an analytical model for activity at BTK is based on its capacity for successively taking into account the di!erent viewpoints on a given activity of the di!erent subjects in the study, and its capacity for revealing possible contradictions between these viewpoints. By de"nition, every person involved in the same activity, shares the same object. Nevertheless, not all are involved in the same actions of transforming the object into an outcome, nor do they have the same historical background. They may, therefore, have di!erent goals and views of the work. If the goals are di!erent, the ways of satisfying those goals also di!er. It is important to take into account a variety of viewpoints to obtain a detailed analysis of the work setting. Inside the dispatchers' team, there are di!erent practices and di!erent views of the work. For instance, two di!erent practices may be observed in the ways the outbound and return dispatchers work. In fact, the starting point of the work of D1 is the list of orders, while the starting point of D2 and D3 is the availability of the drivers. So, even if all are involved in the task of dispatching, each has a speci"c goal, speci"c practices and speci"c tools to achieve his/her task. D1 is responsible for outbound transport. So, she has to allocate transport orders from Liege to available drivers. She starts by matching a list of orders with driver availability in the Liege area. This is indicated on the planning table. D2 and D3 handle return transport. They work towards another goal: "nding nearby return loads for drivers sent out by D1. They use information from D1 or D1's planning table to list &&drops'' (where the trucks will be empty), and they try to "nd loads in these areas. If they have no possible return transport on their own order list, they contact customers in the drop area to try to "nd loads, or they resort to Minitel videotex lists of orders. The Trans-BTK program was designed to support both kinds of dispatchers' work. The greatest value of this software is its shared and updated list of orders. It does not give any information about drivers' availability, so it cannot meet the needs of D2 and D3. This &&contradiction'' implies the need for a new method and new software to shape and support the activity of D2 and D3. Therefore, D2 and D3 use paper notebooks. However, updating these tools is time-consuming. Under these conditions, we could design software that directly "lled computerized notebooks when D1 organizes an outbound trip, and updates them when changes occur in D1's planning. In the same way, a useful computerized system would allow D1 to know when trucks return and are once again available. This tool would compensate for Trans-BTK's lack of information about driver availability. The methods of the dispatch team would then be modi"ed, and time would be gained. According to EngestroK m's (1993) viewpoint, this situation and the contradictions highlighted above could lead to the need for further development of new tools in an ongoing process of change. 4.4. TOOL USE
Human beings mediate their activity through artefacts and tools. In the dispatching room, tools are numerous and spread out into the environment. In their work, dispatchers use phones, networked personal computers, the Trans-BTK program, a Minitel videotex system (to "nd return transport or to list transport they cannot handle) and an access to the World Wide Web (which will eventually replace the Minitel). In addition,
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each dispatcher uses his/her own paper-based tools (e.g. notebooks, maps, post-its, etc.) We want to describe the use of two tools in greater detail, because they seem to play a prime role in mediating the dispatchers' actions. These are the Trans-BTK software and the paper-based planning table. 4.4.1. Trans-BTK software To analyse this artefact's use, we will refer to the distinction between &&tool'' , &&medium'' and &&system'' proposed by Bodker (1996). According to this classi"cation, &&tool'' emphasizes human involvement with materials through a computer application. &&Medium'' emphasizes human involvement with other human beings through the computer. &&System'' emphasizes the perspectives of the human user and data exchange with the computer component. Trans-BTK may be then considered as a &&medium'' between dispatchers and bookkeepers because it is a means of communication that allows dispatchers to send invoices to the billing department. Since it may provide the dispatchers with information (allowing them to organize the order when it is entered, and to recall information about sold orders), the program is also a &&system'', used for communication between dispatchers. If the person who receives the order is not the one who sells it, the program allows other dispatchers to access necessary information. Trans-BTK has an automatic screen update that is activated every 5 min. A sold order is therefore automatically available to each dispatcher. Nevertheless, the artefact does not seem to be fully used, neither as a &&medium'' between dispatchers nor as a &&system''. D1 works from a list of orders she printed the evening before. She uses paper and pencil to update the list when new orders come in. She also writes down the sale of each order on paper and enters all sales into the computer at the end of the day. This means the program's automatic update is useless. Dispatchers prefer other, better-performing media (e.g. verbal communication and peripheral listening) and systems (e.g. personal notebooks) to perform their actions. Why is the Trans-BTK program not fully used as a system by the dispatchers' We can explain the way D1 uses Trans-BTK*entering sold orders only at the end of the day*by the fact that transport does not always go as planned. Changes are more easily made with paper, pencil and an eraser than with the computer program (a change in a computerized order means removing the order from the sold list and putting it back on the sell list). On this basis, we can assume that this tool does not "t the work habits (practices) of all dispatchers. Moreover, the program also forces the return dispatchers to work less e$ciently. Prior to this program, dispatchers "rst looked for available trucks and then matched orders (resulting in the cheapest cost). The Trans-BTK program now requires them to enter the order before "nding a truck, making it more di$cult to respect one of the most important tenets of transport dispatching, namely: minimize empty kilometres. Why is Trans-BTK not fully used as a medium between the dispatchers&& After all, it was designed for that purpose. A possible explanation is that the tool is a weak means of communication. The tool was created to enable one dispatcher to "ll an order received by another dispatcher. The idea was that the program would make a customer's order available to everyone. However, computerized information is less complete than &&peripheral listening'', and additionally, verbal communication among people in a same room
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FIGURE 4. Common information support for the planning activity. The left part of the schema represents the day list orders while the right one represents the week plan table
is faster than entering and reading information on a computer. The workplace is set up for verbal communication, even if that implies working in a noisy environment. 4.4.2. Planning table The other main tool used by dispatchers is the large paper planning table (Figure 4) which represents the actual situation and organizes their work. Columns show truck drivers (truck features are also noted in column headings). Rows show the days of the week. The blanks are "lled in with information on where the truck is loaded and where it will be unloaded. Each dispatcher refers to these tables (one table in the outbound part of the room and another in the return part). Two dispatchers are charged with "lling in and updating the tables. Both use pencils and erasers because the planning is always subject to change. For instance, a truck driver caught in a tra$c jam will be late for the next load, and so dispatchers meet the deadline by allocating that load to another driver. These planning tables function as a system that informs dispatchers and reminds them where the trucks are, what kinds of trucks they are, when they will be available, etc. These tables also serve as a means of communication. For instance, when the head of outbound trips is busy, D3 (head of returns) often refers to the outbound planning table to see when and where the trucks will be unloaded.
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In addition, dispatchers for return and outbound transport use di!erent tools (notebooks, printed lists and so forth), re#ecting the speci"city of their own practice: one basically starts with customers' orders and the other with drivers' availability. The need for two copies of the same planning table implies a loss of time: each copy has to be coordinated with the other and updated several times a day. A shared tool providing dispatchers with real-time lists of drivers' availability would save time. Activity theory basically considers tools as mediators between subject and object. Tools shape the way the subject transforms object into outcome, and individuals use tools to achieve goals. Tools are also built and modi"ed during the activity, as part of an ongoing process of change. We can summarize by saying that during this brief analysis we focused our analysis of activity theory essentially on the role of tools as mediators of human activity, and on the di!erences between the various ways of perceiving the activity of the various participants. Now, let us take a look at how cognitive ergonomics handles the same situation.
5. BTK through the ergonomists’ eyes Cognitive ergonomics focuses on work analysis, on understanding the agents' activity, as it occurs in a given context in relation to artefacts. The approach is essentially pragmatic, experience-driven and conducted through "eld studies. The francophone cognitive ergonomics tradition (De Keyser, Decortis & Van Daele, 1988) prefers "eld observations for understanding and explaining existing situations. Working environments are observed, assumptions are derived and these assumptions drive the conceptualization and the methodology of data collection and analysis. Field analysis in the cognitive ergonomics tradition (Pavard, 1991) is found to be very detailed in event description, and proceeds by di!erent levels of granularity. An initial macro analysis of the work situation aims to give an overall description of the work environment. Next, a micro-analysis aims to detect "ner-grained mechanisms that will become concept-driven and guide the rest of the analysis (Bressolle, Decortis, Pavard & Salembier, 1996). This is how the mechanisms observed in the work situation drive the conceptualization. This implies that we do not necessarily need major theoretical support, but rather a "ne-grained analysis of observable elements and cognitive mechanisms that operate within and assure speci"c functions within the work situation (De Keyser, 1988). Cognitive ergonomics makes a distinction between task and activity (Leplat and Hoc, 1983). Tasks are the explicit aspects of work. Activities are the tacit aspects of work. Activities correspond to how operators deal with the variability and the complexity of the task: how they deal with breakdowns of the system and how they regulate their activities and adjust their behaviour according to their partners and the estimated workload of the group. 5.1. EXPLICIT ASPECTS OF WORK: TASK ANALYSIS
A task is de"ned as a goal to be reached by speci"c means under more or less precise and explicit conditions (De Keyser, 1988; Leplat, 1991). The organization assigns a &&prescribed task'' to the individual. Task analysis aims at studying what an operator or a team of operators is required to do to achieve one or more goals. Tasks are often
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composed of many interrelated parts. Task analysis identi"es these parts and their relationships. In the transport company, the dispatcher's main objective is to provide quality service to the customer. The "rst task is to process an order. This consists of receiving an order, performing the initial processing, choosing the subcontractors (giving priority to regularly used companies) and modifying an order when required by a customer. Planning is the primary task. It consists of estimating and comparing customer orders and available resources (trucks and drivers), and assigning a trip to a driver. Then comes communication, which consists of recording and monitoring the on-going process: passing orders to drivers, entering orders into the Trans-BTK program and monitoring that everything works as planned. The BTK company has several participants performing the various tasks: eight dispatchers, drivers, customers and management. Goals, roles and tasks are the major features in a description of cooperative work. Cooperative work can take many forms, as shown by Zachary and Robertson (1990), and by Benchekroun, Pavard and Salembier (1995). Agents may share goals but perform them independently, agents can negotiate their contributions to cooperative activity and agents may have di!erent goals and still cooperate. Leplat suggests characterizing teamwork by the types of relationship that exist between the team members: (1) task relationship: tasks are carried out together or separately; (2) role di!erentiation: tasks are identical or di!erent; (3) task dependence: tasks may be dependent, interdependent or independent; and (4) goal dependence: goals are shared or they are independent. In the BTK working environment the eight dispatchers perform di+erentiated tasks. Transport orders within Benelux or Germany are processed by the dispatchers who handle outbound Benelux or German transport. A special grouping dispatcher handles orders for grouped loads. These loads are grouped by region or by pallets. Once the loads are grouped, another dispatcher, the outbound dispatcher, "nds a transport company to perform the work. Therefore, the grouping dispatcher's output is one input for the outbound dispatcher. Once the orders are assigned to the drivers, the return dispatcher "nds return loads. This means that the return dispatcher's task depends on both the outbound dispatcher's task and the existing requirements (e.g. "nd a load from Marseille to Liege that matches scheduling demands). The outbound, return and grouping dispatchers have di+erent goals. The outbound dispatcher sells orders of the day by matching them with available resources*"nding available transport companies and drivers. The return dispatcher "nds return loads from the outbound destination. The grouping dispatcher tries to "ll the truck with loads for the same area. The outbound and return dispatchers have di!erent goals and tasks, but they need to cooperate to know where the drivers are. The outbound dispatcher must know when the drivers may be available for the next transport. The return dispatcher must know where the drivers are to plan return transport from nearby areas.
5.2. TACIT ASPECTS OF WORK: ACTIVITY ANALYSIS
An activity is the individual response to the prescribed task. It consists of the mechanisms used by the individual to perform the task. It includes cognitive strategies and
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anticipation mechanisms. In other words, understanding the &&task'' means knowing &&what'' the individual does, while understanding the &&activity'' means knowing &&how'' the individual performs his/her task. As a complement to activity analysis, cognitive ergonomics analyses the context of an activity. In other words, it focuses on understanding a system's components and organization, including the identi"cation of partners and their levels of cooperation. An important part of this analysis consists of determining the complexity of the environmental factors, the working environment, the agents, the task and the activity. At BTK, we can examine the organization of the resource management system, distal and proximal cooperation, locations of the control rooms and the partners, identi"cation of the partners (dispatchers, drivers, managers, customers), communication media and information #ow by telephone, fax and paper, and possible breakdowns (including poor exchange of information needed for planning). Given that the activity is performed in a given time and space, the "rst step is to describe the operations room and how that space is used for cooperative activity. As indicated above, the room is an open space that allows for continuous verbal and non-verbal exchanges between dispatchers. The space also enables the dispatchers to observe one another (e.g. to understand that the colleague is overloaded with telephone calls). Therefore, the infrastructure enables the dispatchers to share an awareness of the situation After the description of the di!erent tasks and roles of the dispatchers, more information can be obtained by analysing how they perform their tasks. The outbound dispatcher sells the orders of the day. How? First she distributes identical workloads to each transport company. She tries to satisfy transport company expectations, and establishes good inter-personal relationships with these companies. She looks for the company and assigns the order. What strategies does she use? She knows that some companies only transport merchandise in Belgium, others only do international transport, etc. This information is clearly colour-coded on her weekly plan (Figure 4): no colour indicates that the company accepts international transport, pink indicates only domestic transport. This plan shows the number of possibilities (e.g. how many carriers do not go to France). Scheduling and opening hours are important considerations. An unanticipated delay in unloading may compromise all system planning. For instance, a delay in unloading will delay the availability of the truck for the next order. This creates the need for additional operations: administrative (informing customers, negotiating ways of getting the truck back on schedule, etc.) and planning (reassigning orders). She may have to sell orders to other transport companies. When this happens, she often divides her workload, keeping the planning activities and allocating the administrative duties to a colleague. What are the tangible features of the process? She uses two main paper supports: the daily order list and the weekly planning table (Figure 4). The night before she prints the daily order list, including all transport to be performed the next day. Yellow indicates early departures, meaning that these are the "rst orders to be processed. She very frequently refers to the daily order list, but uses the weekly planning table as her prime source of information. The daily order list is often superimposed on the weekly planning table. She tries to have all of the right column of the daily order list coloured yellow. She uses the empty back of the daily order list for last minutes orders received after she prints the list. The more scheduling requirements she encounters the more information she
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indicates (hour, etc.) When the driver phones for instructions, she refers to the order list and tells him the load number and the destination of an order. Then she colours that order yellow. At the end of the day, when all the orders have been sold she enters all the information in the Trans-BTK program. The outbound and return dispatchers communicate information on transport destinations in order to match the outbound trip with a return trip. How do they do that? They use two di!erent strategies, focusing on either when or where. The outbound dispatcher announces the driver named &&Albert'' in order to get information on where he is and when he is coming back. The return dispatcher gets the information on where the drivers will go and when. The return and outbound dispatchers see each other around noon every day. The return dispatcher also looks at the weekly plans for &&/V'' information. This information indicates when the driver and the truck will be available at a certain destination, and the return dispatcher has to "nd loads to avoid empty returns.
5.3. COMMON INFORMATION MEDIA FOR PLANNING AND ENVIRONMENTAL RESOURCES
The concept of &&environmental resources'' introduced by Benchekroun, et al. (1995) describes all the potential information resources that an operator can use to perform his task. Di!erent environmental resources can be shared or used separately during several periods of the task. Some of these resources may be preferred by some operators or may be more appropriate under speci"c conditions. One interesting aspect of the concept is that it implies that all types of information media need to be related to several aspects of the environment. These are cognitive state of the operator, his/her cognitive style, state of collaboration of the operators, work complexity and environmental constraints. As a result, there are basic features that seem to predominate when one tries to characterize environmental resources: the environments visual accessibility for one or more operators, the amount of sharing, the operator's capacity for displaying some changes, the range of transparency and mutual awareness of several operators. Given the variability of working situations, and the fact that the workloads may increase for short periods or for unexpected reasons, the operators may change their strategies in order to deal with changes in their environments. Therefore, media preferences are based on characteristics that enable operators to deal with expected or unexpected changes. In the BTK situation, the environmental resources include the computer, paper plan, telephone, etc. We were impressed by the fact that nearly all dispatchers used mainly paper documents. Figure 4 gives an example of the common information media that are used by all dispatchers. What is interesting is that each dispatcher uses his/her own media. Some information is shared and other information is task-speci"c. The outbound and return dispatchers use the same allocation table. This is a paper table, covered with smaller papers. It is fully annotated. We noted that the dispatcher writes with a pencil in order to erase and change data. There are also a few di!erences between the use of this common environmental resource: (1) the outbound dispatcher uses colours for annotating the type of trucks: pink for Belgian transport/yellow for coil transport; (2) the return dispatcher uses the same table, but he does not use the colours. However, beside his general table he has a book for writing more detailed information on each transport (e.g. precise data on known delays, schedules, etc., at loading sites).
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Dispatchers also write important data on the general tables. These are data they need to have permanently displayed for planning (Figure 4) (e.g. truck characteristics, driver names/nicknames, etc.). Dispatchers also use their own system of annotation for planning and coordinating matters with drivers and other dispatchers. Loading and unloading are indicated respectively by C/ or V/. When the information is written in the top of one of the table's cells, it means that the truck and the driver might be available to perform additional transport the same day. When the information is written in the top of one of the table's cells, it means that the truck and driver cannot be reused. The dispatchers told us that these tables are also useful for their colleagues, who can always read information on current and planned transport. These tables are also used for anticipating situations. This activity analysis shows that software could be used for entering "les and keeping company records, but it is not useful for the dispatchers' planning activity (also see Rognin & Derwa, 1996). The dispatchers prefer paper media that provide them with an overall view of the elements needed for planning. Moreover, the dispatchers can and do impose their own rather di!erent use requirements on the computer software. They print two "les: the daily orders to be assigned and speci"c information concerning these orders (loading addresses, time schedule, any need for a loading appointment, information to pass on to drivers, etc.). Then they attach these two printed sheets together to obtain a comprehensive overview of the daily orders to be assigned. 5.4. MUTUAL AWARENESS
An important aspect revealed by the micro-level analysis, apparently crucial in the dispatchers' collective activity, is their mutual awareness, which they describe as &&being able to listen peripherally''. We identi"ed two components of this activity: the extension of the reception format, including re-use of past exchanges, and the distribution of information in the dispatching room. 5.4.1. Extension of the reception format and re-use of past exchanges Several direct exchanges between dispatchers are used in cooperative activity. One example is a mechanism that enlarges the &&reception format'' to include a larger set of participants: an exchange between two participants is overheard by a third, who gets a fourth to participate (Figure 5). During this exchange, past exchanges overheard peripherally by the third partner are re-used. In the following example, the driver asks for new transport instructions (1). Dispatcher 4 gives an instruction to perform order X (2). The driver asks the delivery time (3). The dispatcher looks at the orders for the customer's delivery time (4). The dispatcher informs the driver of the delivery time (5). Simultaneously, dispatcher 3 overhears the exchange between D4 and the driver, and informs D4 that D7 has recently received a phone call changing the delivery time (6). D3 asks D7 for a con"rmation (7). D7 con"rms the order changes to D4. What is relevant in this exchange'' A dispatcher overhears the "rst exchange between D4 and the driver, and intervenes. He refers to a previous exchange he overheard between another dispatcher (D7) and a customer. He calls on D7 to participate in the &&communication space''. D7 had been a bystander to the exchange, and seems not to have listened to the "rst exchange. After being invited to participate, dispatcher 7 con"rms that he has previously obtained information relevant to the current problem.
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FIGURE 5. Example of an extension of the &&reception format'' and past exchange re-use.
FIGURE 6. Example of a question broadcasted to all dispatchers.
5.4.2. Distribution of information in the dispatching room In the following example (Figure 6), a question is asked by dispatcher 2 and is apparently addressed to all dispatchers (1). Dispatcher 5 replies to dispatcher 2, making an assumption concerning the availability of the driver (2), and asks dispatcher 6 (who is in charge
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of this activity) for con"rmation (3). D6 tells D2 (the source of the message) that D5's assumption cannot work because the driver is not available. What is relevant in this interaction? We observe information broadcast by a source who does not know where the information will be processed. Of course, he might be making certain assumptions based on what he knows about the allocation of tasks, and he might expect the return dispatcher to tackle the problem. The information is processed by a receiver, who makes an assumption and calls on someone who has overheard the exchange to evaluate this assumption. The person who overhears becomes one of the main participants and replies negatively to the source. These broadcast exchanges appear to play several roles. They leave tracks for participants who are not directly involved at T1 but who might become involved at T2. This point enables us to enrich the &&responsibility principle'' of Clark and Carlson (1982): it is not always necessary to keep track of what was said, but it is necessary to be able to "nd the relevant information when needed. In the transport company example, the participants'' coordination and the use space is suited to this mechanism. Now, we will turn to distributed cognition to conclude this comparative survey.
6. How does distributed cognition see BTK? Distributed cognition analyses cognition in sociotechnical systems and focuses mainly on how information is represented in the cognitive system and what processes are operating in these representations (Hutchins, 1995a). The system is computerized and mapped by recording how information propagates through the system in terms of &&representational states across media'' (Hutchins 1995b). &&The media refers to internal (individual memories) and external representation (including computer and paper display). The representational state refers to how the various information and knowledge resources are transformed during the work activities'' (Rogers & Ellis, 1994).
By taking the functional system as the unit of analysis, the goal becomes the identi"cation of the structures making up this system (individuals, artefacts, roles and rules), and the analysis of how they are coordinated (Rogers & Ellis, 1994). The information processing properties of systems are therefore directly observable and do not have to be inferred, as they do with individuals. The cognitive properties of systems are described without a need to consider the processes at work inside the individual's head. 6.1. STRUCTURES OF THE FUNCTIONAL SYSTEM: INDIVIDUALS AND TOOLS
Hutchins (1995a) suggests that &&rather than trying to map the "ndings of cognitive psychological studies of the individual, we should map the conceptualisation of the cognitive system on a new unit of analysis: the sociotechnical system.''
This includes a collection of individuals, artefacts and their relations to each other in their environmental setting (Rogers & Ellis, 1994). As the study in BTK is centred on
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dispatcher planning, we assume that the system is located in the dispatching room itself. Mentioning the system immediately raises a number of questions. How do we de"ne its boundaries &&Do we have to limit it physically? The individuals in the system obviously include its permanent workers (the dispatchers), but also the manager, bookkeepers, transport companies, drivers and customers. These participants change the environmental data and modify the system whenever the are present, act or interact. The dispatchers role de"ned and described in the previous sections are of great importance in the work organization. Customer orders are the critical information introduced into the system, and that must be processed by it. When drivers alert dispatchers to their availability on a speci"c day at a speci"c place, they also contribute relevant information into the system. So, customers' orders and drivers' availability can be considered as the system inputs. The selected output is the expected product of cooperative work occurring in the dispatching room, namely transport planning. The sociotechnical system includes people (socio) and tools (technical). Tools are media used to represent information. In the dispatching room, several kinds of representational tools may be identi"ed and di!erentiated. Rogers (1993) di!erentiated highand low-technology tools used in a study of civil engineering practices. Dispatchers also work with various high technology tools such as the phone, jetfax, Minitel and the computer (Trans-BTK program). However, dispatchers generally use paper tools. Representations obtained with the various media (tools) may be either shared or limited to a single individual. For instance, the Trans-BTK program enables dispatchers to consult tables of sell and sold orders and various "les that are automatically updated when any dispatcher modi"es them. The information available in the program is shared. But dispatchers usually do not need to consult the same "le at the same time. Files and tables in the software are potentially shareable rather than actually shared. Planning tables drawn up by D1 and D2 are large and visible representations. Beside those shared representations, it seems that individual representations are used by most dispatchers: D2 uses a personal notebook, D1 works on printed orders, D6 uses paper documents as a personal memory aid. These sets of tools and their representational forms are of great importance in respect of the framework. Their descriptions can be found in the previous sections. 6.2. PROCESSES OPERATING ON REPRESENTATIONS: INTERACTIONS IN THE SOCIOTECHNICAL SYSTEM
One of the main goals of Distributed Cognition is to explain how the structures that make up the functional system (individuals and tools) are coordinated, and how they interact. According to this framework, explanations can be obtained by &&analysing the various contributions of the environment in which work activity takes place, the representational media and the interactions of individuals with each other and their interactional use of artefacts'' (Rogers, 1993).
Distributed cognition focuses on how people interact with each other. Two kinds of human}human interactions are relevant for the system: interactions with the &&outside'' of the dispatching room (transport companies, drivers, customers) and interactions &&inside'' (between dispatchers). This allows to say that the delimited system is open. In the "rst
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type of interactions, information might enter or leave the system. When customers order transport, they introduce data into the system: places of loading and unloading, the goods to be transported, the required height, etc. When drivers or transport companies inform dispatchers of their arrival at a certain time and place, they also introduce information into the system (concerning their availability). When dispatchers interact (either face-to-face or by phone) with drivers and transport companies, giving them instructions on the next transport (where to pick up the load, where to unload and the load code number), information leaves the system. Dispatchers also interact with drivers during transport, to keep tabs on how things are going. Will the driver be on time for the appointment'' When does he expect to unload and will he be available for the next transport&& Information gathered during the transport enables dispatchers to adjust their actions as needed. For instance, if drivers are running behind schedule, dispatchers will warn customers to wait for the truck or will delay the appointment. If the dispatcher has already designated the driver, he or she will "nd another driver and modify the planning table. By knowing in advance when drivers will do their &&drop'' and once again be available, dispatchers can plan the next transport. Distributed cognition examines how in-coming information is propagated and transformed. Information distributed throughout the system may be recorded on various media: orders may be computerized, faxed or remembered by a dispatcher (stored in the dispatcher's memory), driver availability is recorded on the planning table, or stored in the dispatcher's memory. Some information of interest to one dispatcher may be held by another. Interactions within the dispatching room allow for smooth circulation of information between dispatchers. Instead of consulting information resources such as "les in Trans-BTK or the planning tables, dispatchers may ask other dispatchers who might have the desired information. Dispatchers interact with each other continually and are themselves information resources for their colleagues. This process plays a crucial role in circulating information rapidly and in updating information resources needed for planning. This theoretical framework looks at how individuals interact with artefacts, and considers these artefacts as the media used to represent information. It examines both how the various features of the media in#uence the interaction, and how various forms of representation a!ect the coordination of work activity. Throughout the day, dispatchers receive phone and fax orders and enter them in the Trans-BTK program. This means the program has a speci"c role in the system. Trans-BTK is where the di!erent members of the team record orders and make them available to other dispatchers. This is an important role because no one dispatcher would be able to handle all orders entering the dispatching room. By centralizing orders, the program permits cooperative tasks. Anytime a dispatcher enters an order, Trans-BTK becomes a means of propagating that order information. As a result, one dispatcher may sell another dispatcher's order. Obviously, the Trans-BTK's features in#uence the availability of the information. Storing information in the computer with Trans-BTK gives it permanence, but delays access. This contrasts with verbal broadcasting, which is ephemeral but immediate. Verbal information can be produced and received at the same time. The planning tables used by D1 and D2, play another important role in the system. They are directly involved in the planning task, which is not the case with Trans-BTK. Both tables show the dynamics of driver progress, when and where they are loading and
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unloading during the week and on a particular day. The table contains information about drivers schedule, just as Trans-BTK contains information about transport orders. The tables are used as an information resource to allocate transport and as a tool to record the drivers' schedules. During the planning task, the outbound dispatcher needs to know when drivers will be back. So she frequently asks the return dispatcher for the information needed to update her own planning. As soon as she has found drivers for outbound transport (&&storing'' it on the table), the return dispatcher needs to know where the trucks will &&drop''. Both outbound and return dispatchers update their planning. The information cycle starts again when the return dispatcher plans and records the returns on his planning table, and outbound dispatcher needs to know when drivers will be available. These tables enable D1 and D2 to have a global vision of driver trips. The two dispatchers use them as an information resource to plan and to inform other dispatchers. The planning task requires D1 and D2 to use other representational tools. D1 uses the daily order list (order to sell) and D2 also uses a daily notebook. This order list plays an important role in D1's task. It allows her to have a clear view of transport that must be allocated that day. Data about orders and driver availability are distributed among several tools (TransBTK and planning tables), among dispatchers, and is represented both in the environment and inside the dispatchers' heads. As suggested by Zhang and Norman (1994), external representations are an indispensable part of the representational system of any distributed cognitive task. The planning table plays the role of being a reminder for all dispatchers in the work setting. The computerized or paper list of orders also serves as a reminder for what orders have to be sold on a speci"c day. External representations can &&provide information that can be directly perceived and used without being interpreted and formulated explicitly.'' Let us say a driver is scheduled for a speci"c day and job, and is unavailable for the rest of the day. The loading and unloading sites are written at the bottom of the cell. No other information is ever placed in this part of the cell. So when the dispatcher refers to her planning table to "nd a driver, she immediately sees who is and who is not available. Writing this information in a speci"c location on a planning table cell avoids the additional task of looking up the driver's new transport information. Another example is when the order list has an empty cell in the right column. D1 immediately knows that the order still has to be sold. This latter example illustrates another property described by Zhang and Norman: &&external representation can anchor and structure cognitive behaviour. The principal structures in external representations constrain the range of possible cognitive behaviours in the sense that some are allowed and other are prohibited''.
Filling in cells when orders are sold avoids having to "nd a driver for this transport. An empty cell next to the "lled in cell means that a driver must be found for the transport. Human}human interactions and human}tool interactions within the system are very intricate and occur constantly. Dispatchers have to manage hundreds of phone calls with drivers, transport companies, customers and must answer questions posed by colleagues, while managing interactions with various external representations. In the mass of interactions occurring within the system, mapping the planning task requires us to follow the general trajectory of information in real time.
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6.3. MAPPING THE PLANNING TASK
Distributed cognition maps the cognition of a sociotechnical system, and examines how information and knowledge resources are transformed during activities (Rogers & Ellis, 1994), and how information is propagated through the system (Hutchins, 1995b). Information is represented in a speci"c state (oral or written) by a speci"c medium (phone, paper tool, computer display). How is the information introduced into the system? How is it maintained'' How is it transformed &&Where is it propagated'' The customer's order is one of the main pieces of information introduced into the system, and is the information that has to be processed. Where is this order going &&Who receives it'' What does the dispatcher do with it'' Generally, the order is processed over the phone (speech channel) by one dispatcher. Information is initially represented in the memory of the dispatcher. Next, it is ends up on the computer, either directly or after having been written on paper. The order is then con"rmed by fax (writing channel). This short example of order taking is broken down as follows: the customer's order arrives in the dispatching room as a string of spoken words (by phone). It passes through the dispatcher's memory, and becomes words written on paper. It is then transformed into action by typing the order on the keyboard. The order returns to written form on the screen of the computer. The information is clearly moving from one representational state to another by way of di!erent media. Once in the computer, the orders make up part of the sell list. Orders are classi"ed according to the date by which they must be sold and the transport required, and are printed the day before they must be sold. Orders written on the list are then written on the planning table as planned transport for a speci"c driver. When drivers "nish one transport, another is planned, and the driver is informed. When transport is sold, it is moved from the sell list to the sold list in Trans-BTK, and sent to the invoice department.
FIGURE 7. Propagation of the order represented on various media from the reception to plani"cation.
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The &&journey'' is roughly mapped out here, from the introduction of the data by the speech channel, until the order is transformed into planned transport for a speci"c driver on the planning table (Figure 7). This is the most common and easiest way to describe order trajectory. However, the data's &&journey'' could be di!erent and longer. Many orders are processed di!erently. Dispatchers may spend more or less time "nding a truck or driver, more or fewer obstacles may interrupt the process, and di!erent dispatchers use di!erent strategies (implying more or less steps or &&representational states'' to be processed). The order may also pass through the system twice, in di!erent ways: once by computer (written), and once by those who overhear the phone call. This redundancy in data propagation plays a signi"cant role in the dispatching activity. It allows dispatchers to have information on another dispatcher's order, or at least know who has that information. The &&horizon of observation'' is an important concept that preconditions peripheral listening, particularly in cooperative situations. This term refers to the surroundings a person can perceive and monitor in addition to his/her own task. &&¹he main constraint on observing others is the physical setting'' (Seifert & Hutchins, 1992). The physical setting of the dispatching room seems to be appropriate for observing others and interacting with them. All dispatchers work in a spacious room, most facing one another. They can easily hear and see what other dispatchers are doing. This sort of monitoring is part of their everyday practice. Most of the time dispatchers are busy with their speci"c tasks, talking to customers, drivers, transport companies, entering data in the Trans-BTK program or planning. Depending on their cognitive &&availability'', they manage to hear or see what other dispatchers are saying or doing. Overheard information concerning transport, customers, drivers or transport companies is redundant information in the system. The information is held by at least two dispatchers: the direct recipient and the person who overheard it. Overheard information provides the overhearers with partial knowledge of this information, and enables them to know who received the information. In brief, distributed cognition focuses on how information is represented and transformed, its trajectory and how representations (internal and external) are coordinated within the system. It considers the work setting as a thinking system performing cognitive tasks.
7. Discussion 7.1. THE EFFECTS OF A THEORETICAL FILTER
By looking at one work setting (the dispatching room) with di!erent approaches, our intention is to show the e!ects of each theoretical "lter on the analytical results. Certain aspects of the work environment are &&featured'' by each approach, and others remain in the background, or completely disappear. We do not claim the superiority of any one of these three approaches. We simply want to outline each, pointing out major di!erences and similarities. Each of the frameworks breaks down the work situation into distinct units of meaning or of signalling. How "ne grained the analysis is and the choice of analytical units strictly depend on the hypotheses, which are more or less explicit on the basis of the framework
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chosen. Filtering the work situation in this manner produces distortions that are speci"c to each framework. As Devereux points out, it is not the study of the subject, but that of the observer which gives us a means of understanding the essence of the observational situation, and particularly its strategies for determining decisions and making sense out of observations. From that point, it appears imperative to us to make these choices explicit, particularly with regard to the goals of the study, be they a change in the work organization or the design of new technological artefacts. The three frameworks speak for themselves. They give very di!erent pro"les of the work setting. Activity theory focuses on the developmental changes that led to the current situation. This framework examines contradictions within the activity triangle of a single subject (dispatcher or dispatcher's team), or between viewpoints of di!erent subjects (dispatcher, IT specialist, customer and driver). Cognitive ergonomics focuses on how dispatchers achieve their activities and tasks, particularly the cognitive strategies dispatchers use to cope with unpredictable situations. Distributed cognition focuses on how information is represented and transformed, its trajectory and how representations (internal and external) are coordinated in the system. It considers the work setting as a thinking system performing cognitive tasks. 7.2. SHARED AND PARTICULAR CONCERNS THAT EXIST BEHIND THE WORDS
Besides easily perceived di!erences in the general outlines of each approach, there are more di$cultly perceived di!erences and similarities underlying each framework. A prime example is the semantic problem. Theorists from various backgrounds may have di!erent meanings for exactly the same words, giving the false impression that they are dealing with the same concepts. At the opposite end of the scale, they may also assign di!erent words and names to exactly the same concept. Let us focus on three main concepts: activity, tools and artefacts, and representations. 7.2.1. The concept of activity There is a super"cial similarity in the concept of activity used by activity theorists and by cognitive ergonomists. However, in our case study, activity theory is examining transport activity, which is considerably broader than the dispatchers activity studied by cognitive ergonomics. Activity theory uses &&activity'' as a more social and cooperative unit of analysis, going beyond the conventional frontiers of psychology. Contemporary activity theorists (e.g. EngestroK m, 1990) broadly interpret activity to include its socioeconomic and organizational aspects. Cognitive ergonomics views activity in the task, and describes how a dispatcher performs a task by using cognitive strategies. As a result, the term activity has a very di!erent meaning to cognitive ergonomists and contemporary activity theorists. In other respects, EngestroK m (1993) describes activity as a systemic whole, which includes subjects, community and objects, as well as the relationships between those components (mediated by tools, rules and division of labour) in transforming the object into outcome. This vision of activity may be closer to what distributed cognition calls the functional system. Rogers and Ellis (1994) describe the system as a collection of individuals, artefacts and their relationships to one another, which includes participant-tool
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and participant}participant interactions. In other words, the unit of analysis in both frameworks consists of a systemic viewpoint and a focus on the interactions between di!erent components within the system. Nevertheless, in the BTK example, activity theory's &&activity'' refers to the transport of goods (including drivers and customers' actions), while its system mainly refers to what is going on in the dispatching room. Cognitive ergonomics concept of collective activity can be related to the concepts mentioned above. Collective activity is an analysis of group activity as a whole and as a unit with its own laws of operation. So when Von Cranach, Ochsenbein and Valach (1986) discuss a self-active system, they are looking at how the system works and at the processes involved in group action. They also examine the group's information processing, and the way information circulates and develops within the group. Similarly, a major concern in distributed cognition is how the system behaves. In the same respect as in ergonomics, distributed cognition focuses on the propagation of information and more speci"cally on the transformation of information. How does the system process its input'' How does information &&travel'' from one structure (human or artefact) of the system to another &&How do those structures transform the information from one representational state to another'' How does this &&travel'' enable the system to be coordinated&& 7.2.2. Tools and interactions between human and tools Tools and human}tool interactions in the dispatching room are analysed di!erently in these di!erent frameworks. All three analyses examine tools in their context, but not in the same way. Activity theory considers tools as mediators between subject and object. Tools shape the way the subject transforms the object into outcome, and individuals use tools to attain objectives. Tools are also built and modi"ed during the activity, as part of an ongoing process of change. Distributed cognition considers tools as representational media, i.e. media involved in representational states. By media, distributed cognition means the resources used to represent and transform information from one representational state to another, all the way from system input to system output. Both of these frameworks examine the resources used to transform &&something'' (object or input) into &&something else'' (outcome or output). Nevertheless, distributed cognition places emphasis on the representational features of tools and on the roles the various forms of representation } e.g. low}high technology and individual-shared } may play in the coordination of work activities. Distributed cognition does not merely describe tools, it describes the interaction between systems internal representations (inside peoples heads) and external representations (where tools serve as the media). Hutchins (1995b) clari"es the di!erences between media and mediator. He argues that mediating technologies do not separate the user from the task, but rather provide the user with resources to regulate behaviour. In this light, distributed cognition stresses the active role of tools in the cognitive aspects of the system. For instance, knowledge can be distributed to tools, and tools can hold information. This distinctive aspect of distributed cognition di!erentiates it from activity theory, although both frameworks maintain all other speci"cally human aspects (motivation and object).
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Cognitive ergonomics, on the other hand, describes tools as environmental resources related to the activity of the subject, and to the mechanisms performed to achieve the task. Where do individuals "t into these three approaches? Activity theory and cognitive ergonomics start with the subject. Activity theory starts with the subject's perception of his actions, activities and goals, and looks at the variations that exist between the di!erent individual viewpoints. For instance, activity theory clearly shows two di!erent viewpoints in the planning carried out by D1 and D2. By examining cognitive strategies and the adaptive capabilities of subjects, cognitive ergonomics also focuses on the subject. Activity theory and cognitive ergonomics also share the same interest in the goals of subjects. In both frameworks, activity refers to a purposeful, goal-directed e!ort that may or may not be shared with other participants. Nevertheless, there are di!erences. Cognitive ergonomics seems to have forsaken the concept of an overall object in favour of a goal. Activity theory deals with a broader object, considered as collective and above individual goals. In contrast with the other two frameworks, distributed cognition bases its analysis on a systemic viewpoint. It considers the individual as a component of the system, just like a tool. Individuals are seen as media for internal representations that interact with external representations in the dispatching room (i.e. screen displays, tables and tools). Distributed cognition considers system goals more important than subjects' goals. Nardi (1996a}d) points out that a distributed cognition analysis begins with the positing of a system goal, which is similar to the activity theory concept of object, except that a system goal is an abstract systemic concept that does not involve individual consciousness. Activity theory sees the division of labour as a mediator between the community and the object in the process of transforming the object into outcome. It de"nes the division of labour as the explicit and implicit organisation of the community. Cognitive Ergonomists make a distinction between the division of labour and the actual dynamics of labour when confronted by events such as work over#ows and changes in individual workload. Hutchins (1990) talks about the &&nominal division of labour'', which is a reasonable description of what people do. However, he explains that this nominal division of labour is violated in the process of solving the small problems that arise. To summarize, activity theory discusses the explicit and implicit organization of a community, cognitive ergonomics the prescribed and actual division of labour, and Distributed Cognition the nominal and violated division of labour. Whatever the vocabulary used in the three approaches, their analysts are interested in the same dichotomy: prescribed versus contextual division of labour. 7.2.3. The concept of representation The concept of representation is used in the three approaches but does not necessarily refer to the same thing. Representations are rarely studied in activity theory. If they are, it is always in relation to action (e.g. Bardram, 1997). For instance, when D1 works on an order, she has in mind a plan (representation) of actions and actions goals to perform. While it does not appear to be a major reference elsewhere in activity theory, francophone Ergonomics has largely adhered to the concept of operative images
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proposed by Ochanine (1966), a Russian. The concept does not di!er greatly from what Norman (1983) was suggesting when he said that by interacting with their environment, with others and with technological objects, people create internal models of themselves and of the objects with which they interact. These models have to be functional in order to guide people in their use of objects. One of the major goals of a functional representation is to allow the subject to anticipate the result of his own action or of the mechanism that he controls. Therefore functional representations are studied by cognitive ergonomists by focusing on some general characters (Leplat, 1985). Cognitive ergonomists make the distinction between the "gurative aspect (represented by some states of the process) and the operative aspect (characterized by operations that need to be performed). They also focus on representations of actions that are held in common, and the roles of these representations in the coordination of activity. Moreover, distributed representations are not static, they evolve with experience and are progressively built up through exchanges between the participants in a task. Distributed representation has been de"ned as the common functional representation that guides and controls an activity that is cooperatively performed (Leplat, 1991). Distributed cognition is really the framework that assumes that representations are not only in people's heads but also outside. Representations are either internal (individual memories) or external (computer or paper displays). The order, for example, may be represented in writing on the paper planning table, or in typing visible on the screen of the computer or represented in the short-term memory of the dispatcher. A related concept developed in distributed cognition is the representational state, which emphasizes the dynamic aspect of representation. It refers to how information and knowledge resources are transformed during activity, and how the representation of information evolves over time. How does the order entering the system in verbal form (phone call from the customer) end up as a computerized form in the invoice department, or as paper instructions in the truck? As mentioned above, one priority in distributed cognition is to investigate the role that the various forms of representation play in the coordination of work activities (low/high technology and shared/individual technology). In other words, we can say that activity theory and cognitive ergonomics do not have the same concept of representation as distributed cognition. On the one hand, representation refers to representation of action and is mainly internal while on the other hand it refers to representation of information and is mainly external. Just as pictorial representations cannot be separated from their perspective, analyses of a work setting are always oriented by their framework. At the same time, a framework can only provide a partial and "ltered description of the work environment. Therefore, we must acknowledge that a case study is always one of many descriptions of reality. It would be honest to say that there are as many possible descriptions as there are theoretical frameworks. Analysts arrive with their own theoretical backgrounds, and rarely change their frameworks according to speci"c working situations. On the other hand, those frameworks are applied by individuals located in di!erent space and time. The work presented in this paper has been done thanks to the support of the European Commission, Training and Mobility of Researchers programme under the COTCOS contract. We would like to thank VeH ronique De Keyser, Kari Kuutti, Jacques Leplat, Bernard Pavard for thoughtful comments on their respective "elds and three anonymous reviewers who provided very
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helpful comments on a previous version of this paper. While grateful for their reading and their advice, we take full responsibility for any errors or inaccuracies. We would also like to thank Duane Peres for his attentive correction of the English version of this paper.
References BANNON, L. & BODKER, S. (1991). Beyond the interface: encountering artefacts in use. In J. CAROLL, Ed., Designing Interaction: Psychology at the Human}Computer Interface, pp. 227}253. New York: Cambridge University Press. BARDRAM, J. E. (1997). Plans as situated action: an activity theory approach to work#ow systems. In J. A. HUGHES, W. PRINZ, T. RODDEN & K. SCHMIDT ECSCW+97. Proceedings of the 5th European Conference on Computer Supported Cooperative Work, Lancaster, pp. 17}32. UK. 7}11 September. Dordrecht, Netherlands: Kluwer Academic Publishers. BENCHEKROUN, H., PAVARD, B. & SALEMBIER, P. (1995). Design of cooperative systems in complex dynamic environments. In J. M. HOC, P. C. CACCIABUE & E. HOLLNAGEL Eds. Expertise and ¹echnology, Cognition and human Computer Cooperation, pp. 64}76 Hillsdale, NJ: Lawrence Erlbaum. BODKER, S. (1996). Applying activity theory to video analysis: how to make sense of video data in HCI. In B. A. NARDI Ed. Context and Consciousness: Activity ¹heory and Human}Computer Interaction, pp. 147}174. Cambridge, MA: MIT Press. BRESSOLLE, M. C., DECORTIS, F., PAVARD, B. & SALEMBIER, P. (1996). Traitement cognitif et organisationnel des micro-incidents dans le domaine du contro( le aeH rien: analyse des boucles de reH gulation formelles et informelles. In G. DE TERSSAC & E. FRIEDBERG, Ed. CoopeH ration et conception, pp. 267}287. Toulouse: Octare`s. CLARK, H. H. & CARLSON T. B. (1982). Hearers and speech acts. ¸anguage, 58, 332}373. DE KEYSER, V. (1988). De la contingence a` la complexiteH : l'eH volution des ideH es dans l'eH tude des processus continus. ¸e ¹ravail Humain, 51, 1}18. DE KEYSER, V., DECORTIS, F. & VAN DAELE, A. (1988). The Approach of Francophone Ergonomics: Studying New Technologies. In V. DE KEYSER, T. QVALE, B. WILPERT & A. S. RUIZ QUINTANILLA, Eds. ¹he Meaning of =ork and ¹echnological Options. London: Wiley. ENGESTROG M, Y. (1990). ¸earning, =orking and Imagining. ¹welve Studies in Activity ¹heory. Helsinki, Finland: Orient}Konsultit. ENGESTROG M, Y. (1993). Developmental studies of work as a testbench of activity theory. In S. CHAIKLIN & J. LAVE Eds. ;nderstanding Practice: Perpectives on Activity and Context, pp. 64}103 Canada: Cambridge University Press. HUTCHINS, E. (1990). The technology of team navigation. In J. Galegher, R. E. KRAUT & C. EGIDO, Eds., Intellectual ¹eamwork: Social and ¹echnological Foundations of Cooperative =ork, pp. 191}220. Hillsdale, NJ: Lawrence Erlbaum Associates. HUTCHINS, E. (1995a). How a cockpit remembers its speeds. Cognitive Science, 19, 265}288. HUTCHINS, E. (1995b). Cognition in the =ild. Cambridge, MA: MIT Press. HUTCHINS, E. & KLAUSEN, T. (1996). Distributed cognition in an airline cockpit. In D. MIDDELTON & Y. ENGESTROK M Eds. Communication and Cognition at =ork, pp. 15}34 Cambridge: Cambridge University Press. KAPTELININ, V., KUUTTI, K. & BANNON, L. (1995). Activity theory: basic concepts and applications. In B. BLUMENTHAL, J. GORNOSTAEV & C. UNGER, Eds., Proceedings of the 5th International Conference E=HCI195, pp. 189}201. Berlin: Springer. KUUTTI, K. (1996). Activity theory as a potential framework for human}computer interaction. In B. A. NARDI Ed., Context and Consciousness: Activity ¹heory and Human}Computer Interaction, pp. 17}44 Cambridge, MA: MIT Press. LAPLANTINE, J. (1996). ¸a description ethnographique. Paris: Nathan. LAVE, J. (1988). Cognition in Practice. Cambridge: Cambridge University Press. LEPLAT, J. (1985). Les RepreH sentations Fonctionnelles dans le travail. Psychologie Franmaise, 30, 269}275. LEPLAT, J. (1991). ActiviteH s Collectives et Nouvelles Technologies. Revue Internationale de Psychologie Sociale, 4, 337}356.
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LEPLAT, J. & HOC, J. M. (1983). Ta( che et activiteH dans l'analyse psychologique des situations. Cahiers de Psychologie Cognitive, 3, 49}63. LEONTIEV, A. N. (1974). The problem of activity in psychology. Soviet Psychology, 13, 4}33. NARDI, B. A. (1996a). Context and Consciousness: Activity ¹heory and Human}Computer Interaction. Cambridge, MA MIT Press. NARDI, B. A. Ed. (1996b). Activity theory and human}computer interaction. In Context and Consciousness: Activity theory and human}computer Interaction, pp. 7}16 Cambridge: MIT Press. NARDI, B. A. Ed. (1996c). Studying context: a comparison of activity theory, situated action models, and distributed cognition. In Context and Consciousness: Activity ¹heory and Human}Computer Interaction, pp. 69}102. Cambridge: MIT Press. NARDI, B. A. Ed. (1996d). Some re#ections on the application of activity theory. In B. A. NARDI, Ed. Context and Consciousness: Activity ¹heory and human}computer interaction, pp. 235}246. Cambridge: MIT Press. OCHANINE, D. A. (1966). The operative image of controlled object in &&Man}automatic machine'' systems. Actes du X
Activity theory, cognitive ergonomics and distributed cognition: three views of a transport company FRANhOISE DECORTIS Work Psychology Department, FNRS University of Lie% ge, FAPSE B32, 5. Bd. du Rectorat, 4000 Lie% ge, Belgium. email: [email protected]; [email protected] SAMUEL NOIRFALISE- AND BERTHE SAUDELLIJoint Research Centre Ispra, VA21020, Italy
Activity theory, cognitive ergonomics and distributed cognition are three theoretical frameworks used to understand cooperative work settings. In the past, each has used case studies to describe and defend its point of view. However, comparisons are made di$cult by the fact that these studies are usually based on di!erent work settings. This paper describes the application of each framework to exactly the same setting. We believe our approach shows the features that are emphasized and those that are ignored in each framework, enabling us to di!erentiate their relevant questions. We discuss the e!ects of a theoretical "lter on understanding the work setting, the di!erences in the concept of activity, the tools and interactions between humans and tools, the concept of representation, and we look at how a plurality of viewpoints may broaden any interpretation. 2000 Academic Press
1. Introduction An example may be worth a thousand lengthy explanations. Activity theory, cognitive ergonomics and distributed cognition are the three theoretical frameworks used to understand cooperative work settings. In the past, each has used case studies to describe and defend its point of view. However, comparisons are made di$cult by the fact that each study used di!erent work settings. This paper applies each framework to exactly the same setting. We believe this approach highlights the features that are emphasized and those that are ignored, enabling us to di!erentiate the relevant questions posed by each theory. A working environment cannot be described independently of its theoretical framework and the conditions of its observation. How do these theoretical frameworks in#uence our interpretation of the facts &&Why are we using this type of approach'' As Patel and Groen (1993) suggested &&it may be illogical to compare apples and oranges, but it is possible to put them in the same basket. Nevertheless, it is incorrect to conclude that a theoretical framework is superior to another.'' -Now at Laboratorio Multimediale, Universita di Siena, 6 Via dei Termini, Siena, Italy.
1071-5819/00/070005#29 $35.00/0
2000 Academic Press
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It is not our intention to claim superiority for any particular framework. Our approach is primarily heuristic and hermeneutic. Its objective is to successfully handle multiple viewpoints and to determine the analytical pro"le of each viewpoint. This approach avoids what Laplantine (1996) calls the &&ontological illusion'' of unity, identity, stability and persistence of meaning. Using a single viewpoint can give the mistaken impression that it is the best viewpoint. Examining exactly the same situation from various viewpoints necessarily broadens any interpretation. One of our objectives is to understand di!erences and similarities of viewpoints, while taking into account the ontological, genetic and functional aspects of the object being analysed. Another two-part objective is (1) to understand the prominent features of each theory and then to look at the interpretations they generate in analysing work, and (2) to demonstrate the properties of work situations and activities that these frameworks enable us to perceive. We must make it clear that our aim is to contribute to the understanding of theoretical and methodological di!erences in order to help researchers make explicit and appropriate choices for their particular aim. Of course, this does not imply that work analysis is too narrowly focused unless all of these techniques are used, but rather that each produces one explicit interpretation for one work situation, and that this interpretation is one of many possible viewpoints. We picked these three frameworks because each can be used to analyse cooperative activities, even if that is not their only application. We could argue that they have di!erent epistemological orientations. Broadly speaking, distributed cognition has its roots in anthropology, while cognitive ergonomics and activity theory are derived from psychology, with cybernetic and anthropological in#uences present in cognitive ergonomics. Nevertheless, each of these frameworks analyses cognition in real settings, and rejects the conventional symbolic approach where factors are abstracted and studied out of context. Lave (1988) and Star (1996) showed that cognition observed in everyday practice is distributed and &&stretched over''. Activity theory, distributed cognition and cognitive ergonomics share a fundamental indeterminism. All are interested in the &&mysteries'' of workplaces and organizations (Star, 1996) as pathways of information, in distributed access of information (Hutchins & Klausen, 1996) and in regulation loops (Pavard, 1991). We have no pretensions of presenting an exhaustive description of these three complex frameworks. It would be a di$cult challenge to cover any one of them in a su$ciently comprehensive manner. Di!erent if not competing versions of activity theory are widely accepted, and some concepts like unity of consciousness and activity, object-orientedness, internalization}externalization will not be dealt with. The same is true for distributed cognition and cognitive ergonomics. A certain number of choices are made in terms of discriminative concepts. Among these, activity theory emphasizes objects, tools and activity, and a variety of viewpoints that actors have of their subject. Cognitive ergonomics more strongly emphasizes the distinctions between macro and micro analyses of the work situation and between the prescribed task and the activity actually carried out. A major distinguishing characteristic of distributed cognition is its focus on &&representational artefacts'' and the manner in which information is processed by the system (information path and transformation).
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We must caution the reader on two other points. The "rst involves the evolving nature of each of these frameworks, and the fact that we are looking at a single static moment in their existence, namely &&when'' we describe them. However, a framework is constantly faced with new questions and new work situations, and that means the de"nitions of concepts and their relationships constantly develop within these frameworks. It is possible that our view corresponds to speci"c moments in their development. The second point is that we have made a heterogeneous selection. The defenders of cognitive ergonomics insist that it is more a discipline or a "eld of study than a theoretical framework, and that this "eld may itself call upon concepts from activity theory and distributed cognition. This heterogeneity may also bias a comparative approach and lead us to some redundancy when we cover speci"c points. This article aims to present the work situation and the discussion around three main points of the activity, namely tools, interactions between humans and tools, and representations.
2. Methodological issues The comparison of these three approaches to the same work setting obviously has some limits. Any description involves building and reorganizing data. Laplantine (1996) posits that description is writing according to a model, which in turn means building, cutting up and analysing any reality in order to understand it. We do not invent the social processes and events as we witness and record. It is even a mistake to think that we render a faithful copy. We begin to restructure reality as soon as we do "eldwork. Notes or "lms are inevitably a selection of facts from a particular point of view. This means that the best "eldwork and subsequent analysis usually betrays the observer's analytical background, particularly in cognitive science. How do conditions of observation in#uence interpretations of facts'' Here we started from a preliminary report of a study performed on the same site using a cognitive ergonomics perspective (Rognin and Derwa, 1996). The study was conducted in an international transport company (BTK in Belgium), and was part of a larger project aimed at analysing user requirements of various transport companies in Germany, Belgium and Greece. We made observations at di!erent times. First we focused on production, IT and dispatch personnel. This initial contact brought up many questions. Each of us selected and analysed the dispatching work according to di!erent frameworks. We worked separately, taking notes and checking our observations against the concepts of each framework. Then we pooled our individual work and discussed di!erences, similarities and the unique aspects of each approach. Several months later, we made a second set of observations to "ll out our previous description. This work was done in a period of one week. We followed the dispatchers through their workday, making and subsequently transcribing video recordings. The last point that we would like to mention is that we have more extensive experience in using cognitive ergonomics than the other two frameworks. This means that we may have made incomplete or imprecise interpretations of the facts, particularly concerning activity theory and distributed cognition.
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In the following, we begin by presenting the general aspects of the work environment, and we then attempt to demonstrate the concepts that each of these frameworks o!ers for analysing the work situation at BTK.
3. The BTK working environment BTK is an international transport company with several o$ces in Europe. BTK was formed in 1946, and has concentrated on general dispatch work since 1991. The Grace Hollogne o$ce employs 22 people: 10 in the operations department, 8 in the billing department, 2 IT specialists, 1 "nancial manager and the general manager. BTK began dispatching for a paper factory. Since 1991, carriers and logistics personnel have been added to the payroll. About 280 orders are processed each day, which averages out to 20 orders per dispatcher. BTK receives transport orders from customers and subcontracts them to carriers. This is called &&freightage'', and is a speci"c activity in the transport sector. BTK's freightage activity is handled by dispatchers who match customer orders to available resources (drivers and trucks). Independently of any theoretical framework, the dispatchers' work can be described as making the best match between driver and transport order. Dispatchers minimize travel by empty trucks so as to reduce costs, provide the best prices for customers and achieve the greatest pro"ts for the company. This means the dispatcher plans return trips for each truck and driver. If a truck loads in Liege and unloads in Paris, the dispatcher has to "nd a return trip from near Paris to Liege, perhaps via a third stop. This level of planning requires cooperation between the dispatchers. Drivers may be switched from one dispatcher to another to achieve the most e$cient returns or overall routing. All dispatchers have to keep an eye and an ear on every other dispatcher's needs and available resources. The dispatching room (Figure 1) is designed for teamwork. There are seven dispatchers working on truck dispatching, plus two dispatchers responsible for multimodal transport (train/river/sea-container freightage). There are no walls in the dispatching room, and the dispatchers are seated face-to-face. The &&use space'' is organized according to the speci"c needs of the nine dispatchers. They have two telephones, a computer, some paper tables for planning, writing paper, notebooks and maps. The dispatchers are positioned for easy verbal communication. This corresponds with what the operational head of the dispatch room told us: &&a primary principle of this job is being able to listen peripherally.''
The room is designed so that everyone can observe everyone else: at the telephone, entering data into the computer or consulting planning tables. Each member of the group seems to concentrate on his or her task within the respective workspace. In fact, they often exchange information and help one another. An on-line computerized system was installed for real-time information processing and easier communication between dispatchers and the billing department. This information processing system is made up of the following components: the hardware consists of Network Novel, Intra net 4.11, Jet fax (and dedicated PC), PCs, printers; the software consists of an in-house program called Trans-BTK, in addition to conventional programs.
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FIGURE 1. The dispatching room con"guration (D1, dispatcher responsible for outward transports, D2 } D3, dispatchers responsible for return transports, D4, dispatcher responsible for the pallets management, D5, dispatcher responsible for transport from and to Germany, D6, dispatcher responsible for the transports from and to Benelux, D7, dispatcher responsible for the grouping of loads, D8}D9, dispatchers responsible for the multimodal transports).
We begin by describing activity theory's viewpoint on the BTK, then Cognitive Ergonomics' viewpoint and "nally Distributed Cognition's viewpoint.
4. BTK viewed by activity theory Activity theory is a psychological framework originated in Russia and has been developed there and elsewhere over the last 70 years. It has been broadly used more recently in western countries. The unit of reference for activity theory is the &&activity''. Each component of the work setting is explained with reference to the activity or context in which it occurs: &&actions are always situated in a context and are impossible to understand without that context'' (Kuutti, 1996)
The solution o!ered by activity theory is that a minimal meaningful context for individual actions must be included in the basic unit of analysis. Therefore, each action has to be analysed in the activity context in which it occurs. In the BTK o$ce, we look at dispatchers' actions and analyse them in the context of the transport activity. Of interest to us for the purpose of our analysis was the historical, dialectical and hermeneutical viewpoints that form part of activity theory. It is considered historical
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because it looks at the background and developmental aspects of the activity. Activity is studied within the context of ongoing changes. Human practices are seen as a developmental process in which individual and social factors are interlinked. Activity theory can also be considered as dialectical because the analysis aims &&to understand the competing forces at work in relations between the development of the individual and the society in which the individual exists. The features of the individual are explained as outgrowths of basic social forces'' (Bannon and Bodker, 1991).
Contradictions within the activity and with social forces are then seen as the origin of any change. Finally, activity theory can be hermeneutic because it provides an interpretative view of the work setting. It interprets di!erences between the views of the di!erent actors in the work setting as factors of contradiction and incompatibility between di!erent viewpoints that will create pressure for change (EngestroK m, 1993). 4.1. ACTIVITY LEVELS
Leontiev (1974) distinguishes three levels in every human activity: activity, action and operation. Kaptelinin, Kuutti and Bannon (1995) describe action as the central level in the breakdown of activity. Each action is oriented towards a goal. Each goal is functionally subordinated to other goals, up through the hierarchy of goals to the top-level goal, which is not subordinated to any other goal. This top-level goal is the object of the activity. If we move down the hierarchy of actions we might cross the border between conscious and automatic processes. When the individual is no longer aware of his/her behaviour, that behaviour fully depends on environmental conditions, and is de"ned as an operation. This means that activities are made up of actions or chains of actions, which are in turn made up of operations. In our application, the dispatchers' task is accomplished by a set of actions. Each action aims to achieve speci"c goals, for example: gathering needed information concerning an order, "nding the best truck to perform the transport, obtaining the driver's
FIGURE 2. Levels of activity (from Kuutti, 1996).
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agreement or entering the sold order in Trans-BTK. All of these actions are subordinated to the overriding top-level goal of dispatching, i.e. best match of driver trip with customer order. This goal is the object of the activity, and gives meaning to all related actions.
4.2. THE STRUCTURE OF ACTIVITY
EngestroK m (1990) proposes a schematic view of activity involving mediation. &&In the model, the subject refers to the individual or subgroup whose agency is chosen as the point of view in the analysis. The object refers to the &raw material' or &problem space' at which the activity is directed, and which is moulded or transformed into outcomes with the help of physical and symbolic, external and internal tools (mediating instruments and signs). The community is composed of multiple individuals and/or subgroups who share the same general objective. The division of labour refers to both the horizontal division of tasks between the members of the community and to the vertical division of power and status. Finally, the rules refer to the explicit and implicit regulations, norms and conventions that constrain actions and interactions within the activity system.'' (EngestroK m, 1990).
The activity of the subject towards the object is mediated by tools. This means that tools shape the way the activity is performed, and are themselves changed by the activity. In the same way, rules shape the relations between subject and community and are modi"ed by these interactions. Finally, the division of labour shapes the way the di!erent actors of the community take part in the transformation process, and is itself modi"ed by the activity.
FIGURE 3. The structure of the activity, the viewpoint of the entire team of dispatchers (adapted from Engestrom, 1993).
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4.3. VIEWPOINT VARIETY
Activity theory's value as an analytical model for activity at BTK is based on its capacity for successively taking into account the di!erent viewpoints on a given activity of the di!erent subjects in the study, and its capacity for revealing possible contradictions between these viewpoints. By de"nition, every person involved in the same activity, shares the same object. Nevertheless, not all are involved in the same actions of transforming the object into an outcome, nor do they have the same historical background. They may, therefore, have di!erent goals and views of the work. If the goals are di!erent, the ways of satisfying those goals also di!er. It is important to take into account a variety of viewpoints to obtain a detailed analysis of the work setting. Inside the dispatchers' team, there are di!erent practices and di!erent views of the work. For instance, two di!erent practices may be observed in the ways the outbound and return dispatchers work. In fact, the starting point of the work of D1 is the list of orders, while the starting point of D2 and D3 is the availability of the drivers. So, even if all are involved in the task of dispatching, each has a speci"c goal, speci"c practices and speci"c tools to achieve his/her task. D1 is responsible for outbound transport. So, she has to allocate transport orders from Liege to available drivers. She starts by matching a list of orders with driver availability in the Liege area. This is indicated on the planning table. D2 and D3 handle return transport. They work towards another goal: "nding nearby return loads for drivers sent out by D1. They use information from D1 or D1's planning table to list &&drops'' (where the trucks will be empty), and they try to "nd loads in these areas. If they have no possible return transport on their own order list, they contact customers in the drop area to try to "nd loads, or they resort to Minitel videotex lists of orders. The Trans-BTK program was designed to support both kinds of dispatchers' work. The greatest value of this software is its shared and updated list of orders. It does not give any information about drivers' availability, so it cannot meet the needs of D2 and D3. This &&contradiction'' implies the need for a new method and new software to shape and support the activity of D2 and D3. Therefore, D2 and D3 use paper notebooks. However, updating these tools is time-consuming. Under these conditions, we could design software that directly "lled computerized notebooks when D1 organizes an outbound trip, and updates them when changes occur in D1's planning. In the same way, a useful computerized system would allow D1 to know when trucks return and are once again available. This tool would compensate for Trans-BTK's lack of information about driver availability. The methods of the dispatch team would then be modi"ed, and time would be gained. According to EngestroK m's (1993) viewpoint, this situation and the contradictions highlighted above could lead to the need for further development of new tools in an ongoing process of change. 4.4. TOOL USE
Human beings mediate their activity through artefacts and tools. In the dispatching room, tools are numerous and spread out into the environment. In their work, dispatchers use phones, networked personal computers, the Trans-BTK program, a Minitel videotex system (to "nd return transport or to list transport they cannot handle) and an access to the World Wide Web (which will eventually replace the Minitel). In addition,
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each dispatcher uses his/her own paper-based tools (e.g. notebooks, maps, post-its, etc.) We want to describe the use of two tools in greater detail, because they seem to play a prime role in mediating the dispatchers' actions. These are the Trans-BTK software and the paper-based planning table. 4.4.1. Trans-BTK software To analyse this artefact's use, we will refer to the distinction between &&tool'' , &&medium'' and &&system'' proposed by Bodker (1996). According to this classi"cation, &&tool'' emphasizes human involvement with materials through a computer application. &&Medium'' emphasizes human involvement with other human beings through the computer. &&System'' emphasizes the perspectives of the human user and data exchange with the computer component. Trans-BTK may be then considered as a &&medium'' between dispatchers and bookkeepers because it is a means of communication that allows dispatchers to send invoices to the billing department. Since it may provide the dispatchers with information (allowing them to organize the order when it is entered, and to recall information about sold orders), the program is also a &&system'', used for communication between dispatchers. If the person who receives the order is not the one who sells it, the program allows other dispatchers to access necessary information. Trans-BTK has an automatic screen update that is activated every 5 min. A sold order is therefore automatically available to each dispatcher. Nevertheless, the artefact does not seem to be fully used, neither as a &&medium'' between dispatchers nor as a &&system''. D1 works from a list of orders she printed the evening before. She uses paper and pencil to update the list when new orders come in. She also writes down the sale of each order on paper and enters all sales into the computer at the end of the day. This means the program's automatic update is useless. Dispatchers prefer other, better-performing media (e.g. verbal communication and peripheral listening) and systems (e.g. personal notebooks) to perform their actions. Why is the Trans-BTK program not fully used as a system by the dispatchers' We can explain the way D1 uses Trans-BTK*entering sold orders only at the end of the day*by the fact that transport does not always go as planned. Changes are more easily made with paper, pencil and an eraser than with the computer program (a change in a computerized order means removing the order from the sold list and putting it back on the sell list). On this basis, we can assume that this tool does not "t the work habits (practices) of all dispatchers. Moreover, the program also forces the return dispatchers to work less e$ciently. Prior to this program, dispatchers "rst looked for available trucks and then matched orders (resulting in the cheapest cost). The Trans-BTK program now requires them to enter the order before "nding a truck, making it more di$cult to respect one of the most important tenets of transport dispatching, namely: minimize empty kilometres. Why is Trans-BTK not fully used as a medium between the dispatchers&& After all, it was designed for that purpose. A possible explanation is that the tool is a weak means of communication. The tool was created to enable one dispatcher to "ll an order received by another dispatcher. The idea was that the program would make a customer's order available to everyone. However, computerized information is less complete than &&peripheral listening'', and additionally, verbal communication among people in a same room
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FIGURE 4. Common information support for the planning activity. The left part of the schema represents the day list orders while the right one represents the week plan table
is faster than entering and reading information on a computer. The workplace is set up for verbal communication, even if that implies working in a noisy environment. 4.4.2. Planning table The other main tool used by dispatchers is the large paper planning table (Figure 4) which represents the actual situation and organizes their work. Columns show truck drivers (truck features are also noted in column headings). Rows show the days of the week. The blanks are "lled in with information on where the truck is loaded and where it will be unloaded. Each dispatcher refers to these tables (one table in the outbound part of the room and another in the return part). Two dispatchers are charged with "lling in and updating the tables. Both use pencils and erasers because the planning is always subject to change. For instance, a truck driver caught in a tra$c jam will be late for the next load, and so dispatchers meet the deadline by allocating that load to another driver. These planning tables function as a system that informs dispatchers and reminds them where the trucks are, what kinds of trucks they are, when they will be available, etc. These tables also serve as a means of communication. For instance, when the head of outbound trips is busy, D3 (head of returns) often refers to the outbound planning table to see when and where the trucks will be unloaded.
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In addition, dispatchers for return and outbound transport use di!erent tools (notebooks, printed lists and so forth), re#ecting the speci"city of their own practice: one basically starts with customers' orders and the other with drivers' availability. The need for two copies of the same planning table implies a loss of time: each copy has to be coordinated with the other and updated several times a day. A shared tool providing dispatchers with real-time lists of drivers' availability would save time. Activity theory basically considers tools as mediators between subject and object. Tools shape the way the subject transforms object into outcome, and individuals use tools to achieve goals. Tools are also built and modi"ed during the activity, as part of an ongoing process of change. We can summarize by saying that during this brief analysis we focused our analysis of activity theory essentially on the role of tools as mediators of human activity, and on the di!erences between the various ways of perceiving the activity of the various participants. Now, let us take a look at how cognitive ergonomics handles the same situation.
5. BTK through the ergonomists’ eyes Cognitive ergonomics focuses on work analysis, on understanding the agents' activity, as it occurs in a given context in relation to artefacts. The approach is essentially pragmatic, experience-driven and conducted through "eld studies. The francophone cognitive ergonomics tradition (De Keyser, Decortis & Van Daele, 1988) prefers "eld observations for understanding and explaining existing situations. Working environments are observed, assumptions are derived and these assumptions drive the conceptualization and the methodology of data collection and analysis. Field analysis in the cognitive ergonomics tradition (Pavard, 1991) is found to be very detailed in event description, and proceeds by di!erent levels of granularity. An initial macro analysis of the work situation aims to give an overall description of the work environment. Next, a micro-analysis aims to detect "ner-grained mechanisms that will become concept-driven and guide the rest of the analysis (Bressolle, Decortis, Pavard & Salembier, 1996). This is how the mechanisms observed in the work situation drive the conceptualization. This implies that we do not necessarily need major theoretical support, but rather a "ne-grained analysis of observable elements and cognitive mechanisms that operate within and assure speci"c functions within the work situation (De Keyser, 1988). Cognitive ergonomics makes a distinction between task and activity (Leplat and Hoc, 1983). Tasks are the explicit aspects of work. Activities are the tacit aspects of work. Activities correspond to how operators deal with the variability and the complexity of the task: how they deal with breakdowns of the system and how they regulate their activities and adjust their behaviour according to their partners and the estimated workload of the group. 5.1. EXPLICIT ASPECTS OF WORK: TASK ANALYSIS
A task is de"ned as a goal to be reached by speci"c means under more or less precise and explicit conditions (De Keyser, 1988; Leplat, 1991). The organization assigns a &&prescribed task'' to the individual. Task analysis aims at studying what an operator or a team of operators is required to do to achieve one or more goals. Tasks are often
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composed of many interrelated parts. Task analysis identi"es these parts and their relationships. In the transport company, the dispatcher's main objective is to provide quality service to the customer. The "rst task is to process an order. This consists of receiving an order, performing the initial processing, choosing the subcontractors (giving priority to regularly used companies) and modifying an order when required by a customer. Planning is the primary task. It consists of estimating and comparing customer orders and available resources (trucks and drivers), and assigning a trip to a driver. Then comes communication, which consists of recording and monitoring the on-going process: passing orders to drivers, entering orders into the Trans-BTK program and monitoring that everything works as planned. The BTK company has several participants performing the various tasks: eight dispatchers, drivers, customers and management. Goals, roles and tasks are the major features in a description of cooperative work. Cooperative work can take many forms, as shown by Zachary and Robertson (1990), and by Benchekroun, Pavard and Salembier (1995). Agents may share goals but perform them independently, agents can negotiate their contributions to cooperative activity and agents may have di!erent goals and still cooperate. Leplat suggests characterizing teamwork by the types of relationship that exist between the team members: (1) task relationship: tasks are carried out together or separately; (2) role di!erentiation: tasks are identical or di!erent; (3) task dependence: tasks may be dependent, interdependent or independent; and (4) goal dependence: goals are shared or they are independent. In the BTK working environment the eight dispatchers perform di+erentiated tasks. Transport orders within Benelux or Germany are processed by the dispatchers who handle outbound Benelux or German transport. A special grouping dispatcher handles orders for grouped loads. These loads are grouped by region or by pallets. Once the loads are grouped, another dispatcher, the outbound dispatcher, "nds a transport company to perform the work. Therefore, the grouping dispatcher's output is one input for the outbound dispatcher. Once the orders are assigned to the drivers, the return dispatcher "nds return loads. This means that the return dispatcher's task depends on both the outbound dispatcher's task and the existing requirements (e.g. "nd a load from Marseille to Liege that matches scheduling demands). The outbound, return and grouping dispatchers have di+erent goals. The outbound dispatcher sells orders of the day by matching them with available resources*"nding available transport companies and drivers. The return dispatcher "nds return loads from the outbound destination. The grouping dispatcher tries to "ll the truck with loads for the same area. The outbound and return dispatchers have di!erent goals and tasks, but they need to cooperate to know where the drivers are. The outbound dispatcher must know when the drivers may be available for the next transport. The return dispatcher must know where the drivers are to plan return transport from nearby areas.
5.2. TACIT ASPECTS OF WORK: ACTIVITY ANALYSIS
An activity is the individual response to the prescribed task. It consists of the mechanisms used by the individual to perform the task. It includes cognitive strategies and
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anticipation mechanisms. In other words, understanding the &&task'' means knowing &&what'' the individual does, while understanding the &&activity'' means knowing &&how'' the individual performs his/her task. As a complement to activity analysis, cognitive ergonomics analyses the context of an activity. In other words, it focuses on understanding a system's components and organization, including the identi"cation of partners and their levels of cooperation. An important part of this analysis consists of determining the complexity of the environmental factors, the working environment, the agents, the task and the activity. At BTK, we can examine the organization of the resource management system, distal and proximal cooperation, locations of the control rooms and the partners, identi"cation of the partners (dispatchers, drivers, managers, customers), communication media and information #ow by telephone, fax and paper, and possible breakdowns (including poor exchange of information needed for planning). Given that the activity is performed in a given time and space, the "rst step is to describe the operations room and how that space is used for cooperative activity. As indicated above, the room is an open space that allows for continuous verbal and non-verbal exchanges between dispatchers. The space also enables the dispatchers to observe one another (e.g. to understand that the colleague is overloaded with telephone calls). Therefore, the infrastructure enables the dispatchers to share an awareness of the situation After the description of the di!erent tasks and roles of the dispatchers, more information can be obtained by analysing how they perform their tasks. The outbound dispatcher sells the orders of the day. How? First she distributes identical workloads to each transport company. She tries to satisfy transport company expectations, and establishes good inter-personal relationships with these companies. She looks for the company and assigns the order. What strategies does she use? She knows that some companies only transport merchandise in Belgium, others only do international transport, etc. This information is clearly colour-coded on her weekly plan (Figure 4): no colour indicates that the company accepts international transport, pink indicates only domestic transport. This plan shows the number of possibilities (e.g. how many carriers do not go to France). Scheduling and opening hours are important considerations. An unanticipated delay in unloading may compromise all system planning. For instance, a delay in unloading will delay the availability of the truck for the next order. This creates the need for additional operations: administrative (informing customers, negotiating ways of getting the truck back on schedule, etc.) and planning (reassigning orders). She may have to sell orders to other transport companies. When this happens, she often divides her workload, keeping the planning activities and allocating the administrative duties to a colleague. What are the tangible features of the process? She uses two main paper supports: the daily order list and the weekly planning table (Figure 4). The night before she prints the daily order list, including all transport to be performed the next day. Yellow indicates early departures, meaning that these are the "rst orders to be processed. She very frequently refers to the daily order list, but uses the weekly planning table as her prime source of information. The daily order list is often superimposed on the weekly planning table. She tries to have all of the right column of the daily order list coloured yellow. She uses the empty back of the daily order list for last minutes orders received after she prints the list. The more scheduling requirements she encounters the more information she
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indicates (hour, etc.) When the driver phones for instructions, she refers to the order list and tells him the load number and the destination of an order. Then she colours that order yellow. At the end of the day, when all the orders have been sold she enters all the information in the Trans-BTK program. The outbound and return dispatchers communicate information on transport destinations in order to match the outbound trip with a return trip. How do they do that? They use two di!erent strategies, focusing on either when or where. The outbound dispatcher announces the driver named &&Albert'' in order to get information on where he is and when he is coming back. The return dispatcher gets the information on where the drivers will go and when. The return and outbound dispatchers see each other around noon every day. The return dispatcher also looks at the weekly plans for &&/V'' information. This information indicates when the driver and the truck will be available at a certain destination, and the return dispatcher has to "nd loads to avoid empty returns.
5.3. COMMON INFORMATION MEDIA FOR PLANNING AND ENVIRONMENTAL RESOURCES
The concept of &&environmental resources'' introduced by Benchekroun, et al. (1995) describes all the potential information resources that an operator can use to perform his task. Di!erent environmental resources can be shared or used separately during several periods of the task. Some of these resources may be preferred by some operators or may be more appropriate under speci"c conditions. One interesting aspect of the concept is that it implies that all types of information media need to be related to several aspects of the environment. These are cognitive state of the operator, his/her cognitive style, state of collaboration of the operators, work complexity and environmental constraints. As a result, there are basic features that seem to predominate when one tries to characterize environmental resources: the environments visual accessibility for one or more operators, the amount of sharing, the operator's capacity for displaying some changes, the range of transparency and mutual awareness of several operators. Given the variability of working situations, and the fact that the workloads may increase for short periods or for unexpected reasons, the operators may change their strategies in order to deal with changes in their environments. Therefore, media preferences are based on characteristics that enable operators to deal with expected or unexpected changes. In the BTK situation, the environmental resources include the computer, paper plan, telephone, etc. We were impressed by the fact that nearly all dispatchers used mainly paper documents. Figure 4 gives an example of the common information media that are used by all dispatchers. What is interesting is that each dispatcher uses his/her own media. Some information is shared and other information is task-speci"c. The outbound and return dispatchers use the same allocation table. This is a paper table, covered with smaller papers. It is fully annotated. We noted that the dispatcher writes with a pencil in order to erase and change data. There are also a few di!erences between the use of this common environmental resource: (1) the outbound dispatcher uses colours for annotating the type of trucks: pink for Belgian transport/yellow for coil transport; (2) the return dispatcher uses the same table, but he does not use the colours. However, beside his general table he has a book for writing more detailed information on each transport (e.g. precise data on known delays, schedules, etc., at loading sites).
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Dispatchers also write important data on the general tables. These are data they need to have permanently displayed for planning (Figure 4) (e.g. truck characteristics, driver names/nicknames, etc.). Dispatchers also use their own system of annotation for planning and coordinating matters with drivers and other dispatchers. Loading and unloading are indicated respectively by C/ or V/. When the information is written in the top of one of the table's cells, it means that the truck and the driver might be available to perform additional transport the same day. When the information is written in the top of one of the table's cells, it means that the truck and driver cannot be reused. The dispatchers told us that these tables are also useful for their colleagues, who can always read information on current and planned transport. These tables are also used for anticipating situations. This activity analysis shows that software could be used for entering "les and keeping company records, but it is not useful for the dispatchers' planning activity (also see Rognin & Derwa, 1996). The dispatchers prefer paper media that provide them with an overall view of the elements needed for planning. Moreover, the dispatchers can and do impose their own rather di!erent use requirements on the computer software. They print two "les: the daily orders to be assigned and speci"c information concerning these orders (loading addresses, time schedule, any need for a loading appointment, information to pass on to drivers, etc.). Then they attach these two printed sheets together to obtain a comprehensive overview of the daily orders to be assigned. 5.4. MUTUAL AWARENESS
An important aspect revealed by the micro-level analysis, apparently crucial in the dispatchers' collective activity, is their mutual awareness, which they describe as &&being able to listen peripherally''. We identi"ed two components of this activity: the extension of the reception format, including re-use of past exchanges, and the distribution of information in the dispatching room. 5.4.1. Extension of the reception format and re-use of past exchanges Several direct exchanges between dispatchers are used in cooperative activity. One example is a mechanism that enlarges the &&reception format'' to include a larger set of participants: an exchange between two participants is overheard by a third, who gets a fourth to participate (Figure 5). During this exchange, past exchanges overheard peripherally by the third partner are re-used. In the following example, the driver asks for new transport instructions (1). Dispatcher 4 gives an instruction to perform order X (2). The driver asks the delivery time (3). The dispatcher looks at the orders for the customer's delivery time (4). The dispatcher informs the driver of the delivery time (5). Simultaneously, dispatcher 3 overhears the exchange between D4 and the driver, and informs D4 that D7 has recently received a phone call changing the delivery time (6). D3 asks D7 for a con"rmation (7). D7 con"rms the order changes to D4. What is relevant in this exchange'' A dispatcher overhears the "rst exchange between D4 and the driver, and intervenes. He refers to a previous exchange he overheard between another dispatcher (D7) and a customer. He calls on D7 to participate in the &&communication space''. D7 had been a bystander to the exchange, and seems not to have listened to the "rst exchange. After being invited to participate, dispatcher 7 con"rms that he has previously obtained information relevant to the current problem.
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FIGURE 5. Example of an extension of the &&reception format'' and past exchange re-use.
FIGURE 6. Example of a question broadcasted to all dispatchers.
5.4.2. Distribution of information in the dispatching room In the following example (Figure 6), a question is asked by dispatcher 2 and is apparently addressed to all dispatchers (1). Dispatcher 5 replies to dispatcher 2, making an assumption concerning the availability of the driver (2), and asks dispatcher 6 (who is in charge
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of this activity) for con"rmation (3). D6 tells D2 (the source of the message) that D5's assumption cannot work because the driver is not available. What is relevant in this interaction? We observe information broadcast by a source who does not know where the information will be processed. Of course, he might be making certain assumptions based on what he knows about the allocation of tasks, and he might expect the return dispatcher to tackle the problem. The information is processed by a receiver, who makes an assumption and calls on someone who has overheard the exchange to evaluate this assumption. The person who overhears becomes one of the main participants and replies negatively to the source. These broadcast exchanges appear to play several roles. They leave tracks for participants who are not directly involved at T1 but who might become involved at T2. This point enables us to enrich the &&responsibility principle'' of Clark and Carlson (1982): it is not always necessary to keep track of what was said, but it is necessary to be able to "nd the relevant information when needed. In the transport company example, the participants'' coordination and the use space is suited to this mechanism. Now, we will turn to distributed cognition to conclude this comparative survey.
6. How does distributed cognition see BTK? Distributed cognition analyses cognition in sociotechnical systems and focuses mainly on how information is represented in the cognitive system and what processes are operating in these representations (Hutchins, 1995a). The system is computerized and mapped by recording how information propagates through the system in terms of &&representational states across media'' (Hutchins 1995b). &&The media refers to internal (individual memories) and external representation (including computer and paper display). The representational state refers to how the various information and knowledge resources are transformed during the work activities'' (Rogers & Ellis, 1994).
By taking the functional system as the unit of analysis, the goal becomes the identi"cation of the structures making up this system (individuals, artefacts, roles and rules), and the analysis of how they are coordinated (Rogers & Ellis, 1994). The information processing properties of systems are therefore directly observable and do not have to be inferred, as they do with individuals. The cognitive properties of systems are described without a need to consider the processes at work inside the individual's head. 6.1. STRUCTURES OF THE FUNCTIONAL SYSTEM: INDIVIDUALS AND TOOLS
Hutchins (1995a) suggests that &&rather than trying to map the "ndings of cognitive psychological studies of the individual, we should map the conceptualisation of the cognitive system on a new unit of analysis: the sociotechnical system.''
This includes a collection of individuals, artefacts and their relations to each other in their environmental setting (Rogers & Ellis, 1994). As the study in BTK is centred on
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dispatcher planning, we assume that the system is located in the dispatching room itself. Mentioning the system immediately raises a number of questions. How do we de"ne its boundaries &&Do we have to limit it physically? The individuals in the system obviously include its permanent workers (the dispatchers), but also the manager, bookkeepers, transport companies, drivers and customers. These participants change the environmental data and modify the system whenever the are present, act or interact. The dispatchers role de"ned and described in the previous sections are of great importance in the work organization. Customer orders are the critical information introduced into the system, and that must be processed by it. When drivers alert dispatchers to their availability on a speci"c day at a speci"c place, they also contribute relevant information into the system. So, customers' orders and drivers' availability can be considered as the system inputs. The selected output is the expected product of cooperative work occurring in the dispatching room, namely transport planning. The sociotechnical system includes people (socio) and tools (technical). Tools are media used to represent information. In the dispatching room, several kinds of representational tools may be identi"ed and di!erentiated. Rogers (1993) di!erentiated highand low-technology tools used in a study of civil engineering practices. Dispatchers also work with various high technology tools such as the phone, jetfax, Minitel and the computer (Trans-BTK program). However, dispatchers generally use paper tools. Representations obtained with the various media (tools) may be either shared or limited to a single individual. For instance, the Trans-BTK program enables dispatchers to consult tables of sell and sold orders and various "les that are automatically updated when any dispatcher modi"es them. The information available in the program is shared. But dispatchers usually do not need to consult the same "le at the same time. Files and tables in the software are potentially shareable rather than actually shared. Planning tables drawn up by D1 and D2 are large and visible representations. Beside those shared representations, it seems that individual representations are used by most dispatchers: D2 uses a personal notebook, D1 works on printed orders, D6 uses paper documents as a personal memory aid. These sets of tools and their representational forms are of great importance in respect of the framework. Their descriptions can be found in the previous sections. 6.2. PROCESSES OPERATING ON REPRESENTATIONS: INTERACTIONS IN THE SOCIOTECHNICAL SYSTEM
One of the main goals of Distributed Cognition is to explain how the structures that make up the functional system (individuals and tools) are coordinated, and how they interact. According to this framework, explanations can be obtained by &&analysing the various contributions of the environment in which work activity takes place, the representational media and the interactions of individuals with each other and their interactional use of artefacts'' (Rogers, 1993).
Distributed cognition focuses on how people interact with each other. Two kinds of human}human interactions are relevant for the system: interactions with the &&outside'' of the dispatching room (transport companies, drivers, customers) and interactions &&inside'' (between dispatchers). This allows to say that the delimited system is open. In the "rst
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type of interactions, information might enter or leave the system. When customers order transport, they introduce data into the system: places of loading and unloading, the goods to be transported, the required height, etc. When drivers or transport companies inform dispatchers of their arrival at a certain time and place, they also introduce information into the system (concerning their availability). When dispatchers interact (either face-to-face or by phone) with drivers and transport companies, giving them instructions on the next transport (where to pick up the load, where to unload and the load code number), information leaves the system. Dispatchers also interact with drivers during transport, to keep tabs on how things are going. Will the driver be on time for the appointment'' When does he expect to unload and will he be available for the next transport&& Information gathered during the transport enables dispatchers to adjust their actions as needed. For instance, if drivers are running behind schedule, dispatchers will warn customers to wait for the truck or will delay the appointment. If the dispatcher has already designated the driver, he or she will "nd another driver and modify the planning table. By knowing in advance when drivers will do their &&drop'' and once again be available, dispatchers can plan the next transport. Distributed cognition examines how in-coming information is propagated and transformed. Information distributed throughout the system may be recorded on various media: orders may be computerized, faxed or remembered by a dispatcher (stored in the dispatcher's memory), driver availability is recorded on the planning table, or stored in the dispatcher's memory. Some information of interest to one dispatcher may be held by another. Interactions within the dispatching room allow for smooth circulation of information between dispatchers. Instead of consulting information resources such as "les in Trans-BTK or the planning tables, dispatchers may ask other dispatchers who might have the desired information. Dispatchers interact with each other continually and are themselves information resources for their colleagues. This process plays a crucial role in circulating information rapidly and in updating information resources needed for planning. This theoretical framework looks at how individuals interact with artefacts, and considers these artefacts as the media used to represent information. It examines both how the various features of the media in#uence the interaction, and how various forms of representation a!ect the coordination of work activity. Throughout the day, dispatchers receive phone and fax orders and enter them in the Trans-BTK program. This means the program has a speci"c role in the system. Trans-BTK is where the di!erent members of the team record orders and make them available to other dispatchers. This is an important role because no one dispatcher would be able to handle all orders entering the dispatching room. By centralizing orders, the program permits cooperative tasks. Anytime a dispatcher enters an order, Trans-BTK becomes a means of propagating that order information. As a result, one dispatcher may sell another dispatcher's order. Obviously, the Trans-BTK's features in#uence the availability of the information. Storing information in the computer with Trans-BTK gives it permanence, but delays access. This contrasts with verbal broadcasting, which is ephemeral but immediate. Verbal information can be produced and received at the same time. The planning tables used by D1 and D2, play another important role in the system. They are directly involved in the planning task, which is not the case with Trans-BTK. Both tables show the dynamics of driver progress, when and where they are loading and
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unloading during the week and on a particular day. The table contains information about drivers schedule, just as Trans-BTK contains information about transport orders. The tables are used as an information resource to allocate transport and as a tool to record the drivers' schedules. During the planning task, the outbound dispatcher needs to know when drivers will be back. So she frequently asks the return dispatcher for the information needed to update her own planning. As soon as she has found drivers for outbound transport (&&storing'' it on the table), the return dispatcher needs to know where the trucks will &&drop''. Both outbound and return dispatchers update their planning. The information cycle starts again when the return dispatcher plans and records the returns on his planning table, and outbound dispatcher needs to know when drivers will be available. These tables enable D1 and D2 to have a global vision of driver trips. The two dispatchers use them as an information resource to plan and to inform other dispatchers. The planning task requires D1 and D2 to use other representational tools. D1 uses the daily order list (order to sell) and D2 also uses a daily notebook. This order list plays an important role in D1's task. It allows her to have a clear view of transport that must be allocated that day. Data about orders and driver availability are distributed among several tools (TransBTK and planning tables), among dispatchers, and is represented both in the environment and inside the dispatchers' heads. As suggested by Zhang and Norman (1994), external representations are an indispensable part of the representational system of any distributed cognitive task. The planning table plays the role of being a reminder for all dispatchers in the work setting. The computerized or paper list of orders also serves as a reminder for what orders have to be sold on a speci"c day. External representations can &&provide information that can be directly perceived and used without being interpreted and formulated explicitly.'' Let us say a driver is scheduled for a speci"c day and job, and is unavailable for the rest of the day. The loading and unloading sites are written at the bottom of the cell. No other information is ever placed in this part of the cell. So when the dispatcher refers to her planning table to "nd a driver, she immediately sees who is and who is not available. Writing this information in a speci"c location on a planning table cell avoids the additional task of looking up the driver's new transport information. Another example is when the order list has an empty cell in the right column. D1 immediately knows that the order still has to be sold. This latter example illustrates another property described by Zhang and Norman: &&external representation can anchor and structure cognitive behaviour. The principal structures in external representations constrain the range of possible cognitive behaviours in the sense that some are allowed and other are prohibited''.
Filling in cells when orders are sold avoids having to "nd a driver for this transport. An empty cell next to the "lled in cell means that a driver must be found for the transport. Human}human interactions and human}tool interactions within the system are very intricate and occur constantly. Dispatchers have to manage hundreds of phone calls with drivers, transport companies, customers and must answer questions posed by colleagues, while managing interactions with various external representations. In the mass of interactions occurring within the system, mapping the planning task requires us to follow the general trajectory of information in real time.
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6.3. MAPPING THE PLANNING TASK
Distributed cognition maps the cognition of a sociotechnical system, and examines how information and knowledge resources are transformed during activities (Rogers & Ellis, 1994), and how information is propagated through the system (Hutchins, 1995b). Information is represented in a speci"c state (oral or written) by a speci"c medium (phone, paper tool, computer display). How is the information introduced into the system? How is it maintained'' How is it transformed &&Where is it propagated'' The customer's order is one of the main pieces of information introduced into the system, and is the information that has to be processed. Where is this order going &&Who receives it'' What does the dispatcher do with it'' Generally, the order is processed over the phone (speech channel) by one dispatcher. Information is initially represented in the memory of the dispatcher. Next, it is ends up on the computer, either directly or after having been written on paper. The order is then con"rmed by fax (writing channel). This short example of order taking is broken down as follows: the customer's order arrives in the dispatching room as a string of spoken words (by phone). It passes through the dispatcher's memory, and becomes words written on paper. It is then transformed into action by typing the order on the keyboard. The order returns to written form on the screen of the computer. The information is clearly moving from one representational state to another by way of di!erent media. Once in the computer, the orders make up part of the sell list. Orders are classi"ed according to the date by which they must be sold and the transport required, and are printed the day before they must be sold. Orders written on the list are then written on the planning table as planned transport for a speci"c driver. When drivers "nish one transport, another is planned, and the driver is informed. When transport is sold, it is moved from the sell list to the sold list in Trans-BTK, and sent to the invoice department.
FIGURE 7. Propagation of the order represented on various media from the reception to plani"cation.
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The &&journey'' is roughly mapped out here, from the introduction of the data by the speech channel, until the order is transformed into planned transport for a speci"c driver on the planning table (Figure 7). This is the most common and easiest way to describe order trajectory. However, the data's &&journey'' could be di!erent and longer. Many orders are processed di!erently. Dispatchers may spend more or less time "nding a truck or driver, more or fewer obstacles may interrupt the process, and di!erent dispatchers use di!erent strategies (implying more or less steps or &&representational states'' to be processed). The order may also pass through the system twice, in di!erent ways: once by computer (written), and once by those who overhear the phone call. This redundancy in data propagation plays a signi"cant role in the dispatching activity. It allows dispatchers to have information on another dispatcher's order, or at least know who has that information. The &&horizon of observation'' is an important concept that preconditions peripheral listening, particularly in cooperative situations. This term refers to the surroundings a person can perceive and monitor in addition to his/her own task. &&¹he main constraint on observing others is the physical setting'' (Seifert & Hutchins, 1992). The physical setting of the dispatching room seems to be appropriate for observing others and interacting with them. All dispatchers work in a spacious room, most facing one another. They can easily hear and see what other dispatchers are doing. This sort of monitoring is part of their everyday practice. Most of the time dispatchers are busy with their speci"c tasks, talking to customers, drivers, transport companies, entering data in the Trans-BTK program or planning. Depending on their cognitive &&availability'', they manage to hear or see what other dispatchers are saying or doing. Overheard information concerning transport, customers, drivers or transport companies is redundant information in the system. The information is held by at least two dispatchers: the direct recipient and the person who overheard it. Overheard information provides the overhearers with partial knowledge of this information, and enables them to know who received the information. In brief, distributed cognition focuses on how information is represented and transformed, its trajectory and how representations (internal and external) are coordinated within the system. It considers the work setting as a thinking system performing cognitive tasks.
7. Discussion 7.1. THE EFFECTS OF A THEORETICAL FILTER
By looking at one work setting (the dispatching room) with di!erent approaches, our intention is to show the e!ects of each theoretical "lter on the analytical results. Certain aspects of the work environment are &&featured'' by each approach, and others remain in the background, or completely disappear. We do not claim the superiority of any one of these three approaches. We simply want to outline each, pointing out major di!erences and similarities. Each of the frameworks breaks down the work situation into distinct units of meaning or of signalling. How "ne grained the analysis is and the choice of analytical units strictly depend on the hypotheses, which are more or less explicit on the basis of the framework
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chosen. Filtering the work situation in this manner produces distortions that are speci"c to each framework. As Devereux points out, it is not the study of the subject, but that of the observer which gives us a means of understanding the essence of the observational situation, and particularly its strategies for determining decisions and making sense out of observations. From that point, it appears imperative to us to make these choices explicit, particularly with regard to the goals of the study, be they a change in the work organization or the design of new technological artefacts. The three frameworks speak for themselves. They give very di!erent pro"les of the work setting. Activity theory focuses on the developmental changes that led to the current situation. This framework examines contradictions within the activity triangle of a single subject (dispatcher or dispatcher's team), or between viewpoints of di!erent subjects (dispatcher, IT specialist, customer and driver). Cognitive ergonomics focuses on how dispatchers achieve their activities and tasks, particularly the cognitive strategies dispatchers use to cope with unpredictable situations. Distributed cognition focuses on how information is represented and transformed, its trajectory and how representations (internal and external) are coordinated in the system. It considers the work setting as a thinking system performing cognitive tasks. 7.2. SHARED AND PARTICULAR CONCERNS THAT EXIST BEHIND THE WORDS
Besides easily perceived di!erences in the general outlines of each approach, there are more di$cultly perceived di!erences and similarities underlying each framework. A prime example is the semantic problem. Theorists from various backgrounds may have di!erent meanings for exactly the same words, giving the false impression that they are dealing with the same concepts. At the opposite end of the scale, they may also assign di!erent words and names to exactly the same concept. Let us focus on three main concepts: activity, tools and artefacts, and representations. 7.2.1. The concept of activity There is a super"cial similarity in the concept of activity used by activity theorists and by cognitive ergonomists. However, in our case study, activity theory is examining transport activity, which is considerably broader than the dispatchers activity studied by cognitive ergonomics. Activity theory uses &&activity'' as a more social and cooperative unit of analysis, going beyond the conventional frontiers of psychology. Contemporary activity theorists (e.g. EngestroK m, 1990) broadly interpret activity to include its socioeconomic and organizational aspects. Cognitive ergonomics views activity in the task, and describes how a dispatcher performs a task by using cognitive strategies. As a result, the term activity has a very di!erent meaning to cognitive ergonomists and contemporary activity theorists. In other respects, EngestroK m (1993) describes activity as a systemic whole, which includes subjects, community and objects, as well as the relationships between those components (mediated by tools, rules and division of labour) in transforming the object into outcome. This vision of activity may be closer to what distributed cognition calls the functional system. Rogers and Ellis (1994) describe the system as a collection of individuals, artefacts and their relationships to one another, which includes participant-tool
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and participant}participant interactions. In other words, the unit of analysis in both frameworks consists of a systemic viewpoint and a focus on the interactions between di!erent components within the system. Nevertheless, in the BTK example, activity theory's &&activity'' refers to the transport of goods (including drivers and customers' actions), while its system mainly refers to what is going on in the dispatching room. Cognitive ergonomics concept of collective activity can be related to the concepts mentioned above. Collective activity is an analysis of group activity as a whole and as a unit with its own laws of operation. So when Von Cranach, Ochsenbein and Valach (1986) discuss a self-active system, they are looking at how the system works and at the processes involved in group action. They also examine the group's information processing, and the way information circulates and develops within the group. Similarly, a major concern in distributed cognition is how the system behaves. In the same respect as in ergonomics, distributed cognition focuses on the propagation of information and more speci"cally on the transformation of information. How does the system process its input'' How does information &&travel'' from one structure (human or artefact) of the system to another &&How do those structures transform the information from one representational state to another'' How does this &&travel'' enable the system to be coordinated&& 7.2.2. Tools and interactions between human and tools Tools and human}tool interactions in the dispatching room are analysed di!erently in these di!erent frameworks. All three analyses examine tools in their context, but not in the same way. Activity theory considers tools as mediators between subject and object. Tools shape the way the subject transforms the object into outcome, and individuals use tools to attain objectives. Tools are also built and modi"ed during the activity, as part of an ongoing process of change. Distributed cognition considers tools as representational media, i.e. media involved in representational states. By media, distributed cognition means the resources used to represent and transform information from one representational state to another, all the way from system input to system output. Both of these frameworks examine the resources used to transform &&something'' (object or input) into &&something else'' (outcome or output). Nevertheless, distributed cognition places emphasis on the representational features of tools and on the roles the various forms of representation } e.g. low}high technology and individual-shared } may play in the coordination of work activities. Distributed cognition does not merely describe tools, it describes the interaction between systems internal representations (inside peoples heads) and external representations (where tools serve as the media). Hutchins (1995b) clari"es the di!erences between media and mediator. He argues that mediating technologies do not separate the user from the task, but rather provide the user with resources to regulate behaviour. In this light, distributed cognition stresses the active role of tools in the cognitive aspects of the system. For instance, knowledge can be distributed to tools, and tools can hold information. This distinctive aspect of distributed cognition di!erentiates it from activity theory, although both frameworks maintain all other speci"cally human aspects (motivation and object).
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Cognitive ergonomics, on the other hand, describes tools as environmental resources related to the activity of the subject, and to the mechanisms performed to achieve the task. Where do individuals "t into these three approaches? Activity theory and cognitive ergonomics start with the subject. Activity theory starts with the subject's perception of his actions, activities and goals, and looks at the variations that exist between the di!erent individual viewpoints. For instance, activity theory clearly shows two di!erent viewpoints in the planning carried out by D1 and D2. By examining cognitive strategies and the adaptive capabilities of subjects, cognitive ergonomics also focuses on the subject. Activity theory and cognitive ergonomics also share the same interest in the goals of subjects. In both frameworks, activity refers to a purposeful, goal-directed e!ort that may or may not be shared with other participants. Nevertheless, there are di!erences. Cognitive ergonomics seems to have forsaken the concept of an overall object in favour of a goal. Activity theory deals with a broader object, considered as collective and above individual goals. In contrast with the other two frameworks, distributed cognition bases its analysis on a systemic viewpoint. It considers the individual as a component of the system, just like a tool. Individuals are seen as media for internal representations that interact with external representations in the dispatching room (i.e. screen displays, tables and tools). Distributed cognition considers system goals more important than subjects' goals. Nardi (1996a}d) points out that a distributed cognition analysis begins with the positing of a system goal, which is similar to the activity theory concept of object, except that a system goal is an abstract systemic concept that does not involve individual consciousness. Activity theory sees the division of labour as a mediator between the community and the object in the process of transforming the object into outcome. It de"nes the division of labour as the explicit and implicit organisation of the community. Cognitive Ergonomists make a distinction between the division of labour and the actual dynamics of labour when confronted by events such as work over#ows and changes in individual workload. Hutchins (1990) talks about the &&nominal division of labour'', which is a reasonable description of what people do. However, he explains that this nominal division of labour is violated in the process of solving the small problems that arise. To summarize, activity theory discusses the explicit and implicit organization of a community, cognitive ergonomics the prescribed and actual division of labour, and Distributed Cognition the nominal and violated division of labour. Whatever the vocabulary used in the three approaches, their analysts are interested in the same dichotomy: prescribed versus contextual division of labour. 7.2.3. The concept of representation The concept of representation is used in the three approaches but does not necessarily refer to the same thing. Representations are rarely studied in activity theory. If they are, it is always in relation to action (e.g. Bardram, 1997). For instance, when D1 works on an order, she has in mind a plan (representation) of actions and actions goals to perform. While it does not appear to be a major reference elsewhere in activity theory, francophone Ergonomics has largely adhered to the concept of operative images
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proposed by Ochanine (1966), a Russian. The concept does not di!er greatly from what Norman (1983) was suggesting when he said that by interacting with their environment, with others and with technological objects, people create internal models of themselves and of the objects with which they interact. These models have to be functional in order to guide people in their use of objects. One of the major goals of a functional representation is to allow the subject to anticipate the result of his own action or of the mechanism that he controls. Therefore functional representations are studied by cognitive ergonomists by focusing on some general characters (Leplat, 1985). Cognitive ergonomists make the distinction between the "gurative aspect (represented by some states of the process) and the operative aspect (characterized by operations that need to be performed). They also focus on representations of actions that are held in common, and the roles of these representations in the coordination of activity. Moreover, distributed representations are not static, they evolve with experience and are progressively built up through exchanges between the participants in a task. Distributed representation has been de"ned as the common functional representation that guides and controls an activity that is cooperatively performed (Leplat, 1991). Distributed cognition is really the framework that assumes that representations are not only in people's heads but also outside. Representations are either internal (individual memories) or external (computer or paper displays). The order, for example, may be represented in writing on the paper planning table, or in typing visible on the screen of the computer or represented in the short-term memory of the dispatcher. A related concept developed in distributed cognition is the representational state, which emphasizes the dynamic aspect of representation. It refers to how information and knowledge resources are transformed during activity, and how the representation of information evolves over time. How does the order entering the system in verbal form (phone call from the customer) end up as a computerized form in the invoice department, or as paper instructions in the truck? As mentioned above, one priority in distributed cognition is to investigate the role that the various forms of representation play in the coordination of work activities (low/high technology and shared/individual technology). In other words, we can say that activity theory and cognitive ergonomics do not have the same concept of representation as distributed cognition. On the one hand, representation refers to representation of action and is mainly internal while on the other hand it refers to representation of information and is mainly external. Just as pictorial representations cannot be separated from their perspective, analyses of a work setting are always oriented by their framework. At the same time, a framework can only provide a partial and "ltered description of the work environment. Therefore, we must acknowledge that a case study is always one of many descriptions of reality. It would be honest to say that there are as many possible descriptions as there are theoretical frameworks. Analysts arrive with their own theoretical backgrounds, and rarely change their frameworks according to speci"c working situations. On the other hand, those frameworks are applied by individuals located in di!erent space and time. The work presented in this paper has been done thanks to the support of the European Commission, Training and Mobility of Researchers programme under the COTCOS contract. We would like to thank VeH ronique De Keyser, Kari Kuutti, Jacques Leplat, Bernard Pavard for thoughtful comments on their respective "elds and three anonymous reviewers who provided very
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helpful comments on a previous version of this paper. While grateful for their reading and their advice, we take full responsibility for any errors or inaccuracies. We would also like to thank Duane Peres for his attentive correction of the English version of this paper.
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