User Acceptability of Man-Machine Systems

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USER ACCEPTABILITY OF MAN-MACHINE SYSTEMS Simon Richardson I and Harr Otway Commission of the European Communities , Joint Research Centre, Ispra Establishment, Systems Engineering and Reliability Division, 21020 Ispra (V a), Italy

Abstract. Human factors research as it applies to the acceptability of computer-based office systems is described with special emphasis on the importance of their organizational and social contexts. The factors influencing acceptance of man-machine systems are illustrated by case studies and seven dimensions for the evaluation of acceptability are proposed as are five principles to be observed when making evaluations. Implications of human factors research for the safe operation of hazardous industrial facilities are discussed. Keywords. Human factors; man-machine interface; user acceptability; industrial risk; organizational behaviour; ergonomics.

INTRODUCTION

In organizational settings, users are also becoming concerned about the selection of technology, demanding products that are easy to use and which do not negatively affect the quality of their working lives. Their awareness of possible negative effects is to a large degree the result of early implementations of new technology which were based purely on economic considerations. Adopting a more user-oriented approach does pose a number of problems for systems designers: quite apart from the problem of coming to terms with unfamiliar human factors, knowledge there is a potential conflict between what users want and what the designer is able and willing to give (Konstam, 1980). There is also the problem of de fining who the "user 11 is; there is seldom a homogeneous user group with a consistent set of skills and goals, yet these are variables which will strongly influence the ultimate success of the designers' work when it has been implemented (Cuff, 1980; Kidd, 1982; ZOltan and Chapanis, 1982; van Muylwijk and colleagues, 1983) .

Human factors is a general term which describes a set of skills, knowledge, expertise and processes used to facilitate the interactions between humans and machines. The current interest in its application comes from three main directions: organizational demands for economic gains through the greater productivity made possible by new technology; user demands for more satisfying and comfortable work environments; and the awareness that the largest uncertainties in the safe operation of hazardous industrial facilities are attributable to human per formance and organizational factors. In economic terms, organizations seek to obtain adequate returns on capital investment in new technology. Sometimes the justification will be based on increased productivity or on the elimination of jobs, but the economic benefits cannot be realized unless the new technology also meets other basic requirements. These include the obvious one of being capable of performing the tasks required of it, but also the more subtle one of not imposing upon the users conditions of use which exceed their physical and psychological resources. Early systems rarely achieved this, largely because of pressures on designers to develop cost-effective systems based upon increased productivity alone. Rarely, if ever, were designers trained in or made aware of the importance of physical and psychological factors which influence human performance. These effects were often revealed to them only when the systems as implemented failed to live up to expectations. Tb promote potential economic benefits as the prime reason for implementation of new systems has since been proven to be unrealistic in view of the inter-relationships which exist between user satisfaction and productivity (Hopwood, 1983). User demands are more complex, partly because they have been stimulated by the availability of new technology in the consumer market, helping to create an increasingly discriminating and aware public. lAt the time the paper was written Simon Richardson was a visiting scientist at the JRC from the HUSAT Research Centre, University of Technology, Loughborough, Leicestershire, U.K.

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Interest in the safety dimension of human performance is rather more recent, with the possible exception of commercial aviation. Its importance was dramatically demonstrated by the release of methyl isocyanate from a fertiliser plant at Bhopal, India, which killed at least 2000 people and permanently disabled as many as 100,000. The accident was caused by the employment of unqualified personnel who were poorly trained in both routine maintenance and emergency procedures; it was further aggravated by a local management decision to shut down some safety-related equipment for economic reasons and by poor communication between local plant management and the home office. The immediate cause of the Seveso chemical reactor accident in Italy was the failure of operating personnel to adequately cool a pressure vessel, but they had not been provided with updated procedures by management after the capacity of the plant had been increased. The severity of the Three Mile Island nuclear power plant accident in the USA was due to the failure of the operating crew to diagnose and respond to a stuck pressure relief valve. However, investigation disclosed that this failure had been recognized as pcssible in this type of plant and warning given to plant management, who had neglected to bring them to the attention of opera ting personnel.

S. Richan iso ll allti H. 0(\\;1\

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In this paper we will propose a conceptual framework for the evaluation of the man-machine interaction as well as a strategy for its evaluation across a number of relevant dimensions. We will draw primarily on the experience of computer-based office technology and discuss its application to the problem of hazardous process plant operations. Throughout , we will argue for taking a wider view of the man-machine interface than that of traditional physica l ergonomics. Although ergonomics is of crucial importance, i t is necessary to take a broader systems view and evaluate techno l ogy in its "real life" organizational and socia l contexts. Systems must be technically able to do what they are supposed to do, they must be suited to the physical and psychological resources of the users and they must not impose organizational or communication patterns that interfere with their overall functioning. Finally, i t is concluded that these factors are of vital importance to the management of risk from hazardous industrial facilities and that research for such appl ications is needed .

THE COMPLEXITY OF THE MAN-MACH I NE INTERFACE One of the traditional human factors approaches in evalua tion involves the concept of "synergy ", how well the systematized task is fitted to human capabilities . Its theoretical basis is in concepts such as the principle of least effort or in studies of attention span, vigilance , memory, etc., which have helped to establish ranges and to l erances of physiological and psychological data with respect to human performance. The main drawback to this approach is its tendency to focus on the interface between user and machine, however, human perfor mance is not only a function of screens and keyboards and their immediate physical environments. For exampl e , in the industria l accidents mentioned earlier , the "man-machine interface was visible on a number of l evels: the interface between maintenance workers and hardware; the interface between operating crews and the software of system control; and the interface between management and the overall plant . In other words , the interface is IOOre complex than that existing between , say , a process plant operator and his control panel. It is fairly easy , under controlled conditions , to measure the probability of typical operators responding correctly to a certain type of emergency alarm . However, in a real operating environment , the organization itself may dominate operating safety in ways that defy quantification , e.g. by giving insu fficient training so tha t opera tors are not ab l e to understand the consequences of their work, or by speci fying procedures or communication channels which ensure failure if followed in an unforeseen situation . 11

Even less amenable to formal analysis may be the effects upon human performance of working in an organizational climate where motivation has been destroyed by blocked careers , favouritism , or unfair compensation policies . Attitudes , IOOtivations and the organizational environment all play a part in determi ning how systems are used , even where user discretion is theoretically not al l owed . This complexity may be further demonstrated by examining three case studies of the implementation of computer - based office systems.

Case Study 1: Training and Support A commercial company had been using an advanced office system for some time . It incorporated facilities for e l ectronic messaging, text storage and retrieval , and text editing and was intended for use by managers, engineers and secretaries at two locations some 300 km apart. The company decided to

evaluate the system to deterr.line if it should be upgraded or withdrawn. Among the evaluations proposed was a human factors study to establish how well the system met task needs, how easy it was to use , the perceived con s equence s of using it and , finally, the adequacy of the support and training provided. System use, as monitored by the c o mpany Data Base Administrator (DBA) had showen a steady increase, however , there were notable differences i n amount of use between North and South. The human f3ctors evaluators also found that user ratings of the systems were also qui te different . Despite the fact that the work at both sites was essentially the same, South used the system much r.lOre extensively, not only in frequenc y of use but also in the variety of tasks performed. Co~plaints about the system in the South focused on technical proble~s , such as response time or editing software, while in the North they were concerned with training and infrastructure. The system was a success in the South , but a failure in the North . Upon investigation it was found that the differences between the sites were primarily due to the fact that the DBA , the training officer , and the technical expert on the system all had their per manent offices in the South, making only infre quent visits to the North when required to solve specific problems . For example, when the trainer visi ted the North , he scheduled a t ,,,o hour training session with each user . I n that time he attempted to teach a l l the system facilities, irrespective of the job needs of the individual user. In the South, users had the opportunity of frequent informa l contacts with the trainer and systems experts, th u s were able to resolve minor problems as they arose and to gradual l y become fami l iar with the system. They were ab l e to direct questions easily to the DBA and trainer alike , focusing their further training on specific task require ments as and when needed . Note that the work was the same and the sy,ter.l was the same, the only difference between success and failure , both on the individual and organizational levels, was the difference in training and user support. Nevertheless, for organizational reasons , similar training and support facilities could not be instal l ed in the North . The system was ultimately rejected by the North users and had to be withdrawn. Case Study 2: Motivation and the Management of Change A large insurance company wanted to install micro computers in its offices; as a first stage they would be used to carry out calculation s of pay ments to be made to clients. 'TWo sections were selected as the pilot sites for the system which was de veloped by a design tear.l from the head office. The design method used was conventional systems analysis , supplemented by advice fror.l "user representatives", one from each of the two sections. The user representat i ves were senior staff who were no longer involved in the actual tasks to be computerized . A human factors evaluation was carried out about six months after implementation of the pilot system , after a cost-productivity analYSis suggested that much greater gains could have been achieved and that an expansion of the system should have been clearly justified. The human factors evaluation found exceptionally low levels of user satisfaction, despite a wide s pread belief that the technology could , in principle , be of value to them. The method of implementati o n was a great source of user concern. Equipment had been "dumped " on the

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251

sections without explanation or adequate warning,

supplied to top management as the "official" sta-

extra help provided for the period of parallel

tus of production.

running were an inappropriate mix of skill and experience, and insufficient provision was made for users to practise on the system. This caused con-

DIMENSIONS OF USER ACCEPTANCE

siderable conflict between the sections and the head office (who had managed the implementation)

These example s de=nstrate that the reasons for the failure of systens can extend far beyond the

when output was not maintained. The user representatives became the target for criticism from both

user-machine interface in the narrow sense, making manufacturer-supplied ergonomic data of very limi-

users and head office. One of them gave up his responsibilities while the other identified himself with the design tea~ in defence of the sys tem instead of the other way round.

Further, it suggests that rating scales alone are not likely to be able to capture the multi-dimensional character of user perceptions of systems and

ted relevance to the prediction of acceptability.

that evaluations should not be left until after Users also felt that their jobs were less satisfying and required less skill than they had before. On analysis it was found that the design team had chosen to concentrate on computerizing

the more technically challenging part of the users' jobs . They had devised a series of rulebased heuristics to compute payments, a task pre-

viously done by users. The users felt that these were impcrtant skill based parts of their jobs which gave them a certain amount of autonomy in relation with clients. Other aspects of their work which were not computerized, such as some of the routine inputting of data, were felt by the users to be onerous and

boring.

systems have been installed, but should be an on-

going process which begins before design work. For example, a study of the frequency of keystroke errors as a measure of keyboard usability, tells us nothing about the users motivations, the training he has had, the way in which the new system was announced, the changes in social relationships and communication channels that the system has caused, and so on. To ensure that a holist~c view is used in eva l uation, we shall define "user acceptability" as the ratios of costs to benefits, for user and organization alike, resulting from the implementation of new technology. For the organization, costs will involve capital investment of resources in the new

The system was re-designed after the evaluation and more attention was paid to the management of

system, whereas the benefits would be primarily

change and to the method of implementation. A

the perception of costs and benefits that matters:

subsequent evaluation showed higher ratings of user acceptance and less concern about de-skilling.

benefits might include improved career prospects, increased status in the organization, a decrease in routine work; costs could include the fear of having to master a new way of working, a weakening of established working relationships, increased

Case Study 3: The Organisation

increases in productivity. For the user,

it is

Crozier and Pave (1984) report a study of the computerization of the work scheduling and production functions in a small French factory. The schedu-

formality and rigidity in procedures, etc. Where costs exceed benefits for either party (or for a

lers, who were also responsible for customer con-

the pluralistic nature of the users in an organization), the system is unlikely to be successful (Richardson, 1982; Eason, 1984).

tacts, saw the new system as a means of bringing production under proper control. They believed that

significant proportion of the users, considering

if they could monitor work in progress using a

computer system, they could establish control over the production department, thereby providing bet-

In this framework user needs, functionality and the organizational context become vital components

ter customer service.

in the evaluation of acceptability. Since these

In practice, the transparency created by the new

computer system lasted only a short while because it did not take account of the frequent ad hoc demands upon production schedules which made it impossible to stick to preprogrammed procedures. For example, the scheduling department had regular negotiations with customers, which often resulted in changes in order size or specifications

with the effect of lengthening or shortening production times. The production department had al -

factors influence human performance they are as important, if not more so, than simplistic measures of efficiency and effectiveness in the conventional sense . Researchers have identified six elements, derived from extensive experience of system evaluations, which are crucial to accep-

tability and must be considered from ginning of a project's life cycle. A existing evaluation methods (Pouson, further applied research leads us to

the very be review of 1984) and postulate

their rearrangement and the formulation of a se-

ways had to carry out unscheduled operations, such as the repair of damaged orders which was cheaper

venth. They are as follows:

than re-doing them. In fact, the computerized system did not allow for the existing patterns of

-

the technical design process

-

the organizational and social environment the hardware, software and physical environment

work and the social behaviour necessary to get the

work done, with the result that production costs increased. In addition,

since the old system of

communication had been dismantled when the new computer system was introduced, and the new system did not allow for the realities o f re-scheduling, the result was that there was even less informa-

tion available to the schedulers about actual production status. They were obliged to go to the shop floor to visually check t h e status of orders while customers waited on the telephone. In this case the method chosen to organize the

work made it impossible to do the work, setting off a power struggle between departments that previously had been able to co-operate. The final so -

- the job design - the user support and training -

the implementation process the human and organizational impacts.

The Technical Design Proces s Traditionally, design methods are organized around an expert model, one that assumes that the designer is best qualified to find a technical solution to the problem. Dissatisfaction with solutions generated in this way has led to a number of radical design methodologies where the u s er, from the outset, considered to be the "owner" of the design

(Damodaran, 1983; Mumford,

1983) . The designer is

lution was that everyone agreed to ignore the new

considered as a contractor who is not authorized

computer system and to return to the old methods of work, letting the computer-generated schedules be

ners . In fact,

to make design decisions independently of the owthe user mu s t authorize design as

s.

252

Richa rclso n and H. Ol\,·a \·

it proceeds on the basis of information provided by the designer and other qualified sources of ex pertise. This sys tem has been successfully used when sys tems are designed "in house but has also been used in the development of off- the - shelf systems, such as the Xerox Star. 11 ,

From the earliest stages of design, when decisions are being made as to where , when and how new technology is to be introduced , users shoul d partici pate in the design process . This is necessary if the design is to meet task requirements , avoid exceeding user capabilities and give recognitio n to the significance of organizational factors . The Organizational and Social Environment By its very nature, the new technology involves information . Information is characterized by more than just content and form, it can also mean power . Its routes define organizationa l structure , if facilitates communication , co-ordination and control. It involves people and their needs for achievement, se lf actualization and recognition . When new technology is introduced , it can threaten not only the individuals directly affected, but also other people whose supply of information , and perhaps power, may also undergo subtl e changes. It would be unrealistic to rely merely on the fo rmal organization chart , documented procedures and job descriptions to provide a complete picture of communication and information networks . In reality, organizations make their decisions in ways not reflected in these formal documents , especia l ly when variations from norma l operations occur. Informal structures exist which are used to avoid or to short-circui t the formal ones in the interest of getting the work done and to ensure a supportive work environment . Great care must be taken that the flexibility provided by informa l arrangements is not destroyed by the new system . Hardware and Software Interfaces and the Physical Environment There is a large body of literature with recommendations and checklists for providing appropriate interfaces for the design of hardware, software and the physical environment (Cakir, Hart and Stewart , 1980; Grandjean, 1980; Damodaran , Simpson and lVilson, 1980; Bailey, 1982; etc.) . Cl early , it is at these interfaces tha t system and user performance are most easily observed, monitored and controlled , however, this should not be taken to mean that evaluation is simply comparison of designs to checklist recommendations. These checklists are best thought of as range setting devices; their actual use can pose some unexpected difficulties such as evaluating trade - offs between standards , and knowing under which condi tions specific standards are meant to apply . One problem is that technology changes rap i dly and some standards are not applicable to new forms of input or output devices. They may also constrain design teams searching for innovative sol utions which might prove more valuable than existing codes 0 f prac tice. Noise , temperature, lighting , humidity , workplace layout , furniture , etc ., can all contr ibute to the experience of fatigue , anxiety and stress which can result in high error rates , lower productivity and high level s of absenteism. Observational checks can be easily carried out using existing checklists. However , as with checklists for hardware and software, they must be considered with respect to individual perceptions and experiences . I ndivi dua l differences have been found to have an important influence on the significance that should be attached to checkl is t observa tions.

Job Design Interactions between user and the new technology wil l de fine some par t 0 f the users job func tion and its structure, with consequent impacts upon the job design. Evaluation must examine the na ture and extent of these impacts and the costs and benefits perceived by the user as a result. Criteria for assess ing job design do exist (Davis and Taylor, 1979 ; Kelly , 1983 ; Cilen , 1975) , however , many sten from particular philosophical positions which may not be relevant to all organizations . Job enlargement or job enrichment may be expressed as design objectives as well as increased productivity, improved human performance or enhanced quality of working life. The final decision about what constitutes a good job design is made from a combination of organizati onal needs and user requirements . Only a systematic analysis of the latter , made with the users involved in the particular application , can generate appropriate job design criteria . User Support and Training The introduction of new tec hno logy, or changes to existing systems, generate the need for both or ganizational adjustment and us er adaptation to it (Eason , 1983; Damodaran , 1980; Briefs and col leagues, 1983). There will be initial needs for user reaSsurance or for training and instruction in new operating procedures and processes. The provision of mechanisms for this organizational learning to occur must be carefully planned and continued throughout the l ife of the system. The strategies used can be evaluated as a basis to identify areas where user uncertainties have been removed or anxieties reduced. The Implementation Process The objective of introducing new technology is for the benefits it can give to organization and user alike. I-Ihatever the technology, some kind of organizationa l change , perhaps unintended , is to be anticipated (Bjorn-Andersen and Eas c n, 1980 ; Eason , 1982). Such change must be planned for. In addition, implementation invariably causes di3 ruptions in work; provisions must be made to ensure that they are minimized, that adequate resources are provided to cater for normal workload and that the inevitable break - in problems are dealt with swiftly and without unnecessary stress . User and Organizational Impacts Organizations usually have plans for recruitment, for assuring worker health and safety , etc., but the introduction of new technology may require that all personnel-related policies be r eviewed. For ins tance , is the IIVDT opera tor a new job, r equir ing new skills , or is t he VDT simply a tool used to support work on an existing post? There may , in addition , be a bureaucratization of organizational structure of shifts in power from tradi tional line managers to new service functions f o r some kinds of work . Further, as many organizations are able to reduce levels of middle management with the introduction of management informa tion systems , there may be additional stresses exerted on top management who have access to IlDre information but without some traditional sources of emotional support and the sharing of responsi bility (lIynne and Otway , 1983). At lo·.:er levels in the o rganization, individuals may feel that their own e mployme nt is threatened , that t ;,eir functional roles in L~e organization may change , and that the extent of their power or influence may be changed . Less directly , job satisfaction , skills, career structures , motivation, etc . may also change . 11

LseI' :\cceptability of I\lall-l\ lac hill c S\stellls EVALUATING ACCEPTANCE

economic and technical dimensions , but a l ong human

a nd socia l dimen s ion s as well _ Paradoxica ll y, the The seven dimensions of acceptance suggest that a

radical shift is needed from traditional methods o f evaluation to take a more balanced and holistic view of human performance . Implicit in this new

mode l

commitment to a comprehensive evaluation of user acceptance of man - machine systems is , at the same

time , the method for assuring that they are accepted by users _

is that user , task and context variables all

interact with , and are interdependent with technology . The techniques of evaluation must, therefore , achieve two things . First , they must examine the processes and content of syste~ design and second , they must examine the social and organizational con -

DISCUSSION AND CONCLUSIONS Humans and machines are only two components of a

system; they interact in the contexts of physical ,

texts in which the system is to be used _

o rgani zatio nal and social environments . I n our dis cussion of computer - based off i ce systems we have

On this basis the evaluation of user acceptance i s not a one off exercise , or a series of audits to

systems are i Mp le mented can l ead to their failure, a failure that, in the final analysis , is no le ss

tried to show how neglect of the contexts in which

be carried out after implementation is complete _

real than if the technology itse lf had failed to

It has characteristics which more near l y resemble a strategy than a particular set of constrained techniques , and is , therefore , flexible enough to

per form.

cope with changes over time and with different

ure are a loss of investment by the organization

applications in varied contexts .

and also a possible loss of face on t he part of

Evaluation should begin prior to proposed changes ,

this does not alwa ys happen_ Sometimes , as in the

and should initially define the components of the

case of the French manufacturing plant , resourceful

existing sociotechnical system, describe its boun -

employees manage to bypass the new system or to keep the o ld system operating in parallel to carry

In office settings, the implications of system fail -

those who proposed and designed it. However , even

daries and its interrelationships _ It then forms a major par t of design development , where design decisions are taken with reference to the baseline

data developed at the first stage _ Fur ther direct studies should continue to review and to read just the baseline and to e l aborate upon design features throughout the project development life cycle and even continue after implementation.

The precise method of evaluation will depend upon the specific application , but the essential ingred ie nts are:

1 ) Stud ie s of the socio - technical systems likel" to be affected by technological change should be carried out prior to the formulation of user requirements and we l l in advance of any techni-

cal speci fication . These stud ies should identi fy such aspects as communication flows, criteria for job satisfaction , formal and informa l organizati ona l

structures , and a procedural ana -

l ysis which notes the factors preventing the functioning of planned procedures_ These studies wi ll be a statement of human and organizational objectives that the deve l opment is to achieve and also what it should not affect . 2) Throughout project development the re should be user involvement, but not only to partic i pate i n experiments to test out different technical options . The users should have a joint decision

making role, equa l to that of the deSigners whose task is to offer technical options for solving particular problems_ Participation in the decision making process implies 3cceptance of the results of those decisions. 3) Where experimentation is to be used it should be treated systematicall y and follow appropriate ~ethodo l ogies to establish representative samp l es and to analyse data using statistical tech niques so that valid co nclusions can be drawn .

4) Continuous reference should be made to the ori ginal terms of reference set by the socio-technical systems study in order to as sess the ef fects of all decisions as they are made. These checks should be made by the users. 5) After implementation is comp lete , periodic audits shoul d be und ertaken to identify and correct deficiencies in design or implementation .

Evaluation of user acceptance shoul d be regarded as an integral part of design , complemen tar y to traditional systeM analysis and other design tools_ In fact , it i s a strategic methodology to ensure that not only synergy is obtained between the human and the machine , but that broader social and technica l

factors are also kept in balance. In this way ,

planning and design move forward not only along

out tasks made impossible by t he new arrangement.

The fai lure of the new system is often not conscious l y acknowledged in such cases and it may even be proclaimed an "off i c ial" success , even though

its fu ll potentia l

is not being realized_

In t he case o f process plant ooerations with im p l icatio ns f or public safety ,

the situation is

quite different . Failures on the human dimension can have disastrous consequences that cannot be

concealed , e _g_ Bhooa l, Seveso and Three Mile Is land. Examination of these and other accidents sugges ts that their causes are often found not only in the immediate interface between human and machine but in the orga ni zationa l and social vironments in which they function .

en -

Human factors research has played a role in the design o f complex and soph i st i cated control systems, particular ly in the av i ation industry . However,

for a variety of reas ons (Otway and Misenta , 1980) , the pilot ' s job cannot be compared with the process operator ' s. The organizational dimens i ons of motiv.J.tion , compensation , prestige , job satis f ac -

tion , etc . h3ve been largely stabilized in the aviation industry due to a combination of i nhe ren t job characte ri stics and industry efforts t o ~ro ­ vide satisfactory conditions_ Paradoxica lly, this has allo,,,ed orga n izationa l v ariables to be treated as constants so that research cou l d focus on the

man - machine interface and on modelling the behaviour o f t he .o ilot. Modelling has, i n turn, contributed to automation of the pilot ' s j ob , as in the two - pi l ot Boeing 767s and the Airbus A- 310 _ Negative effects are nO\4 feared on the organiza tional dimensions , with

corres~nding

effects on

public saf ety, if the automated job leads to deski ll ing , boredom , complacency and demotivation

(Iveiner , 1985) _ De spite extensive human factors two - thirds of aircraft accidents are thought to be at least partially caused by human

research , errors .

If emphas i s on interface design has led to organi zational dimensions being neglected for the pilot , there is even greater potential for .D rcblems in hazardous process operations , where not even inter-

face design has received much attention_ A pos sible excep tion is the nuclear industry which has focused on h~~an factors in the wake of the Three ' li le Is l i'lnd accident , but mostly on ergonomic as ~cts . Th e nuclear industry is also different fro m most

~rocess

industries in that it has always been

subjected to stringent government controls and it has had a historica l emphasis on safety throughout its develooment.

qecent rjccidents have demonstrated the relati.onshio betl;een public safety and the behaviour of the geople and orqanizations that o~erate hazardous facili ties. Certain changes , wi th far-reaching impl i cations , are taking place as a result. Legal definitions of liability are being expanded , particu larly with respect to the chemical industry where charges of personal and criminal liability ha ve been made against corporate off icials. Likewise , liability for the mere exposure to risk , as evidenced by precursors of disease such as chromosome breaks or the presence of chemicals in blood, has been accepted by courts. It is , therefore , becoming increasingly difficult to obtain liability insurance whi le, at the same tLme , government regulations are becoming more demanding (Baram , 1984) . For example , there are laws in many countries which require that industry inform those at risk of the nature of the hazards to \,.,hich they are ex!'Osed and the measures to take in the event of an accident This means that cOITlJ!licated risk analysis results must be communi cated clear l y and honestly , but without causi!1g un due alarm , to lay publi cs and workers . A more robust "science" of risk analysis, capable of ~rovidinq more conclusive results , could help meet the demands of changing legal , insurance and regu l atory regimes . This requires some basic work on methods and critical physical - chemical phenomena, but a ll areas with large uncertainties need to be addressed. One of these is the human and organizaticnal dimensions of ind'Jstria J. risk (Singleton, 19E4) .

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