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Time pressure and stress as a factor during emergency egress
Safety Science 38 (2001) 95±107
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Time pressure and stress as a factor during emergency egress F. Ozel College of Architecture and Environmental Design, Arizona State University, Tempe, AZ 85287-1605, USA
Abstract While human beings, as information processing entities, use environmental cues during route selection in ®re emergencies, time pressure, i.e. the limited time available to people, and the stress created by the physical threat of ®re, can aect how they process environmental information. This study focuses on theories on decision making under time pressure and stress, and applies them to the area of emergency egress and route selection during ®res. Narrowing of the range of cues attended to under time pressure, the emphasis placed on the negative aspects of decision alternatives and ®ltering of information are some of the examples of distortions in the information processing capacity of the individual. Spatial behavior greatly relies on how environmental information is utilized, and therefore any miscalculations in the use of this information can lead to ineective spatial, thus exiting, behavior. Furthermore, while some degree of stress can lead to a bene®cial vigilance in information processing, further increase in stress can create a hypervigilant state, limiting the capacity of the individual to process environmental information eectively. The article also provides examples from investigative reports of ®res to further discuss the topics addressed. # 2001 Elsevier Science Ltd. All rights reserved. Keywords: Decision making; Time pressure; Stress; Emergency egress
1. Introduction Various situations in everyday life, as well as crises, require making decisions while pressed by deadlines. The individual equipped with limited information handling capacity tries to balance the desire to accurately choose options which ultimately maximize his/her bene®ts and the equally important need to reduce the cognitive strains of the given decision task (Ben Zur and Breznitz, 1981). The rate of information processing could increase due to the rise in the amount of data to be processed or due to the decrease in the time available for processing. Such an E-mail address: [email protected] (F. Ozel). 0925-7535/01/$ - see front matter # 2001 Elsevier Science Ltd. All rights reserved. PII: S0925-7535(00)00061-8
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increase in information load is de®ned to be the time pressure on the decision task at hand. Regardless of which de®nition is taken, it is clear that decision making during ®re emergencies is time pressured. The decision process during ®res is also aected by the emotional state of the person involved. While the time constraint in itself is enough to create stress, the existence of a physical and very real threat to one's life can add considerable stress and aect the decision making capacity of the individual. In fact, the characteristics of ®re emergencies have already been de®ned as stress inducing by a number of researchers (Wood, 1979; Proulx, 1993). Here, the term stress is used to indicate ``psychological stress designating unpleasant emotional states evoked by threatening environmental events or stimuli'' (Janis and Mann, 1977). Typically, decision-making models that are process oriented focus on psychological processes and how they evolve over time. Studies in this area are increasingly drawing on methods and theories from cognitive psychology (Ranyard et al., 1997). Among these models is the one developed by Janis and Mann (1977). The signi®cance of this model for emergency decision situations originates from the fact that it was ®rst developed for emergency decision tasks and then applied to more general decision conditions. The premise of Janis and Mann's theory is that human beings make decisions under contrasting conditions that determine whether the stress engendered by decisional con¯ict will facilitate or interfere with vigilant information processing. Vigilance ``results in thorough information search, unbiased assimilation of new information, and other characteristics of high quality decision making'' (Janis and Mann, 1977). The degree of stress during an emergency determines how vigilant a person is in processing information regarding the emergency situation. This model is compatible with Simon's (1960) analysis of the role of motivation and emotion in controlling cognitive behavior, where human being is de®ned as a ``serial information processor''. Both of these approaches are in-line with the premise that human beings are information processing entities, and distortions in the capacity to process information can have an impact on the decisions made. This premise is also relevant for decisions made by occupants in ®re emergencies. The behavior of people in ®res is a total decision-making process where the circumstances created by ®re and smoke can modify, distort and change the mechanisms by which people make decisions. These distortions are primarily due to the limited time available for decision making while the stress created by the physical threat to life also becomes a major factor. 2. Decision making during ®res Many ®re safety researchers (Canter et al., 1980; Bryan, 1981) de®ne human behavior in ®res to be episodic in nature, where occupants display a variety of action sequences. Usually each episode has an identi®able goal and a number of observable actions associated with this goal (Ozel, 1994). While the sequence of the decision processes in ®re emergencies is important, action plans regarding the execution of each individual episode are equally important. For example, the decision to alert
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others must be complemented by an implementation plan, or the decision to exit requires that an exit be selected for exiting. Thus, while goals such as ®ghting the ®re, evacuating, investigating, etc., represent decision making as transitions from one episode to another, what implementation strategies to use represents decision making within an individual episode. Decision making within an episode as well as between episodes can be aected by less-than-ideal or not-optimally-vigilant (Janis and Mann, 1977) strategies people use in information processing due to time pressure and stress (Fig. 1). In the stress model developed by Proulx (1993), decision making in emergencies is de®ned in terms of the emotional stages users can experience. She argues that additional information provided during an emergency can serve to reduce the negative eects of stress and motivate evacuation behavior. Proulx (1993, p. 138) also recognises the ``ambiguous, incomplete and unusual nature of the information on which to base the decision making process'', especially at the early stages of a ®re emergency. Thus, the researcher primarily focuses on the nature of the information that is available at each stage of the decision process. This is important in complementing the theory that de®nes humans as ``information processing entities'' during emergencies. On the other hand, by studying the distortions in the decision making mechanisms, other researchers such as Janis and Mann (1977) and Miller (1960) direct their attention to the internal decision making mechanisms. This also represents the basic premise of this study, which states that given the same set of information, people may attend to information dierently depending on the degree of stress and the amount of time pressure they experience. Among the theories that concentrate on the internal decision mechanisms, Svenson and Maule (1993) introduce the theory of Dierentiation and Consolidation where decision making is regarded as an active process that allows the gradual differentiation of one alternative from others until it is ®nally chosen. In this model there is a strong distinction between the processes at the pre-decision phase verses the post-decision phase. The changing nature of the conditions during a ®re emergency
Fig. 1. Decision making under time pressure and the episodic nature of human behavior during ®res.
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can minimize the distinction between pre- and post-decision phases. As soon as an occupant makes a decision and starts to implement it, conditions might change, forcing the occupant to reassess the situation and make a new decision. Occupants are rarely committed to a single decision during a ®re emergency, as evidenced by behavioral episodes (Bryan, 1981). Therefore, while the occupant continues to re-assess his/her current goal to see if there is a need to change it (pre-decision phase), he/she also continues to process other relevant information in order to execute the current decision at hand (post-decision). Therefore, decisions are layered over each other, with pre and post phases continuously overlapping. Proulx (1993) also recognizes the overlapping nature of the decision processes in ®res, where episodes are represented in a spiral form, each level representing a certain degree of stress reached which then blends in with the next phase of the decision process. In the past, the eects of stress and time pressure on group behavior or social behavior have also been considered as a factor in decision making in ®res. This literature generally tends to focus on crowd behavior, emphasizing competitive verses cooperative behavior during exiting. Among these, Sime (1983) and Chertko and Kushigian (1999) summarize many of the theories (such as by Mintz, 1951; Brown, 1965; Kelley et al., 1965, etc.) on crowd behavior while focusing on the tradeos between the individual's objective thinking as opposed to his/her behavior based on his/her expectations of the behavior of the others in the crowd. The role of stress and time pressure in crowd behavior is out of the scope of the present study, since the focus here is primarily on exit behavior, cue utilization and the individual's information processing capacity under time pressure and stress. 3. Information processing under time pressure and stress Among the internal processes that modify and distort decision making under time pressure and stress are coping mechanisms which determine how available information is processed, and bolstering mechanisms which can directly act on the nature of the decisions made by changing the desirability of a decision in the positive direction and by limiting the objective use of the information that is attended to. 3.1. Coping mechanisms Miller (1960) argues that during decision making under time pressure, people use a number of coping mechanisms such as: 1. acceleration, which is the processing of information at a faster rate; 2. the avoidance of decision, which may express itself in random choices or making choices according to momentary standing out characteristics of choice alternatives; and 3. ®ltration, which can be viewed as a compromise strategy, where only subjectively important data are chosen for consideration, to cope with time pressured and unavoidable conditions.
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These mechanisms actually reduce the time pressure, and enable the decision maker to decide in a relatively consistent and organized way. They are more likely to be used when the threat of possible negative outcomes is stronger than the threat of not considering all information. In simplifying as proposed, a decision maker accepts some distortion in his or her subjectively ideal judgment policy. 3.2. Bolstering Montgomery and Svenson (1989) argues that decisions are governed by the desire to choose an alternative that is better at least in one attribute and equally good as all others. To achieve this, people tend to restructure the information about a decision problem in the desired direction of the dominance of one alternative. This is called ``bolstering'' and Janis and Mann (1977) also identify ``bolstering'' as a mechanism in ``defensive avoidance'' process when a decisional con¯ict exists. Whenever there is diculty in reaching a decision due to con¯icting decision alternatives, the occupant can use bolstering mechanisms where, rather than objectively weighting dierent alternative decisions during a ®re emergency, they might restructure the information in the direction of a desired decision. For example, once the decision to exit is made, exit choice decision can be bolstered in favor of one alternative over others. On the other hand, bolstering can also happen between episodes by favoring one course of action over other possible courses of action, such as preferring to investigate the ®re rather than deciding to exit, indicating defensive avoidance through bolstering. 4. A model for decision making in ®re emergencies Janis and Mann (1977) identify four dierent phases for decision making depending on the level of stress for any single decision. These mechanisms need to be re-examined within the context of the episodic nature of human behavior in ®res and the coping mechanisms used. While Proulx (1993) de®nes the levels of stress in terms of their potential eect on the emotional state of the individual (levels are: control, uncertainty, fear, worry, confusion) as well as the nature of the information such as whether it is irrelevant, task-relevant or ambiguous, Janis and Mann de®ne the stages of the decision making under stress in terms of the level of vigilance with which information is processed. Since the latter primarily focuses on the processes that are internal to the individual, it was seen as more applicable to the concepts investigated here and thus was further examined. 4.1. Uncon¯icted inertia Where the credibility of the initial source of information is assessed to see if the environmental cues indicate the existence of an immediate threat that might impact the occupant's welfare. At this point the occupant might rightfully or mistakenly choose to ignore the evidence and ignore the threat. At the beginning of the ®rst
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episode of behavior, an occupant might be at this phase, ignoring ®re alarms or unusual cues such as noise in the corridor. This can also be attributed to defensive avoidance where the occupant refuses to pay attention to the initial cues due to multiple coping mechanisms. The real danger of uncon¯icted inertia is that the occupant might loose too much time, leaving little time for further action. This can increase the potential for high time pressure further down the line. At this stage (®rst loop in her model), Proulx (1993) primarily attributes defensive avoidance to the ambiguous nature of the information, which can in fact be an important factor. 4.2. Uncon¯icted change Where the occupant starts to believe the existence of a threat and becomes more emotionally aroused. At this point, since the occupant is still under the belief that there is time to escape or the threat is not serious enough to pose a real danger, the level of stress or time pressure is not high enough to create real distortions in the information capacity of the individual. Nevertheless the occupant starts becoming more vigilant. The level of stress at this point completely depends on the background of the occupant and the speed with which the conditions deteriorate in the building. At this level, an occupant may go through several episodes of behavior, and the sequence of decisions can be impacted by the desire to ®nd the most appropriate course of action before the decision to exit is made (Fig. 2). 4.3. Defensive avoidance As the person's level of stress becomes more intense, distortions in the decisionmaking capacity can increase. At this point, the occupant also becomes aware that the time is running out, and thus time pressure starts taking its toll on the person's capacity to process information. This is probably the most likely point where the decision to exit will be made, if not already made by the occupant. At this point, one can expect to see an increase in the use of coping mechanisms such as ®ltering, paying attention to the negative dimensions of the situation, accelerated processing of information, bolstering etc. Or the occupant may choose to ``pass the buck'' to someone else for decision making, for example, by joining to a group or a person he/ she is aliated with and allowing others to make the decisions for him/her. At this
Fig. 2. Behavioral episodes and stages of vigilance. The numbers for the episodes are only for demonstration purposes, since the total number of episodes can vary depending on the individual circumstances. Not all of the stages of vigilance will be experienced by all people.
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point, aliation may play an important role, as evidenced by the aliation models of behavior in ®res (Sime, 1983). 4.4. Hypervigilance As long as the occupant maintains the belief that he/she can still reach safety, vigilant tendencies will remain active. But as the situation gets more and more hopeless and the occupant tries to execute his/her decision to egress, the stress level increases even further with very high levels of time pressure. Janis and Mann (1977) identify the most extreme case of hypervigilance as ``panic'', which has often been incorrectly depicted in the popular media as the ``typical'' mode of behavior in ®res. Hypervigilance is evidenced by the use of intense ®ltering of information at highly accelerated rates of processing. Such high levels of coping mechanisms can ultimately lead to errors in decision making. Since usually by this time in the decision sequence, the occupant is committed to exiting, distortions in information processing are more likely to impact the implementation of the ``Egress'' episode. In the literature that investigates ``panic'' in ®res, many researchers assert that behavior identi®ed as ``panic'' with hindsight can be seen as a perfectly appropriate behavior when the individual's speci®c circumstances during a ®re incident are investigated. In fact, Sime (1983, p. 22) states that the scienti®c validity of the concept of panic in a ®re context has been in serious contention in recent discussions, and thus brings no operational de®nition. Although dicult to bring an operational de®nition, the concept of panic has been investigated for individuals as well as for groups (Sime, 1983) and crowds (Chertko and Kushigian, 1999) in ®re situations. Sime points out that the traditional ``panic model'' assumes that individuals that belong to homogeneous populations compete with each other for limited exits, whereas ``aliative model'' asserts that people attempt to escape in groups of two or more implying a more cooperative rather than a competitive model for exiting. On the other hand, Chertko and Kushigian (1999) provide a discussion of dierent theories on ``panic'' behavior for crowds and for groups with less group cohesion, and recount six major ®res in terms of crowd behavior. The intention here is not to discuss dierent theories on ``panic'' behavior, but to identify potential areas that can complement such theories by looking at the distortions in the information processing capacity of the individual as a possible factor in erratic egress behavior, often incorrectly attributed to panic. Among such distortions is the possibility of people ``not attending to all relevant information'' either due to ®ltration process or due to the accelerated rate of information processing, in spite of the ready availability of such information. Thus, in some cases, the behavior termed ``panic'' can be explained by how people make decisions under time pressured conditions. For example, rushing to a familiar exit, or to a lobby exit; or going to a friend's room instead of directly exiting can be explained by how people ®lter information under time pressure ``by attending to more subjectively signi®cant data''. How much erratic decisions can be attributed to bolstering rather than to panic must also be studied both within and between episodes, since bolstering is de®ned as one of the mechanisms for defensive avoidance.
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Obviously, it is also necessary to investigate ``hypervigilance'' as a possible internal reason for behavior that is considered (with hindsight) inconsistent with rational behavior. 5. Time pressure and spatial behavior As discussed earlier, when an occupant is in a hypervigilant state, it is very likely that they are also trying to evacuate the building (Fig. 2). Therefore, one can expect to ®nd the distortions in the information processing capacity of the individual to impact exit behavior and thus spatial behavior the most. Information coming from environmental cognition literature suggests that spatial behavior is largely eected by the nature of the physical environment around us. In the past, several researchers (Weisman, 1979; Ozel and Weisman, 1984; Passini, 1984) have successfully argued that a physical environment, by virtue of its inherent characteristics, such as the degree of perceptual access, the degree of dierentiation, general con®guration, etc., aects way ®nding and spatial behavior of its occupants under emergency (Ozel, 1994a,b; Ozel et al., 1997) and non-emergency conditions. De®ciencies in processing environmental information due to time pressure and stress can have profound eects on spatial behavior. When a decision maker attends to certain dimensions only due to a ®ltration process, these dimensions consequently have greater impact on his/her judgments than they normally would. There is some data that supports the theory that people attend to negative dimensions more when under time pressure. If he/she focuses on negative evidence, the person sacri®ces awareness of the extent of positive outcomes to be expected, and vice versa. In the context of decision making under certainty, Wright (1974) found that time pressure caused attribution of more weight to negative information in purchase options. Later Ben Zur and Bretnitz (1981) found similar results in an investigation of decision making under risk. Under time pressure conditions, choices were less risky and a tendency for preferring negative dimensions was also found. This argument has some important implications on exit choice behavior in ®res. There is some evidence in the ®re safety literature that people prefer more familiar routes during ®re incidences (Sime, 1983, 1985). This ®nding is also in-line with the theory on cognitive mapping and spatial behavior. The preference for familiar exits becomes understandable when such routes are immediately available to the cognition of the individual and thus perceived to be the less risky choice, since any other route will have an additional risk factor of losing one's way and not being able to spot the exact location of the alternate exit. Therefore, with the introduction of time pressure and stress, preference for familiar exits is further emphasized. Negative associations with a particular route have in the past led some people to prefer other exit routes. In one such case, in a nursing home ®re (Bickman et al., 1977), three out of four exits were labeled with signs indicating that they should only be used in case of emergency and that an alarm will sound when used. Furthermore, patients were penalized by the nurses if they used these exits during daily functioning
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of the building. During an actual ®re incident, only six out of more than 100 residents used the three peripheral exits with negative labeling and thus negative associations, although many of them later indicated that they knew the location of these exits. Occupants who were interviewed after the ®re incident indicated that the use of these doors were prohibited. Under the pressure of time and stress people were not able to concentrate on the positive aspects of alternative routes, such as closeness to the present location of the occupant, not having to go through the ®re area, less crowding, etc., but used the negative implications instead. Therefore, by prohibiting the use of alternate exits during non-emergency conditions, we can not only limit the formation of cognitive maps, but can also inadvertently create negative associations and biases, highly limiting the likelihood of their use in emergencies. Training and education can help to reduce the problem of attending to the negative dimensions of an emergency situation, and to increase the ability to pay attention to relevant cues for decision making. In discussing ®re exit doors with murals on them in a shopping mall, Sixsmith et al. (1988) argue that ``Given that way ®nding has to be quick and ecient in the event of a ®re, . . .®re doors should be readily recognizable. . .''. Thus, the ®ltration of cues is identi®ed as a problem in exit recognition, indicating that ®re doors must provide unambigious cues due to the speed of information processing needed under such conditions (i.e. time pressure), possibly distorting or delaying people's perception of relevant cues. Although this is clearly an extreme case where cues were hidden by murals, in a complex environment such as a shopping mall the overload of environmental cues (store windows, lighting, etc.) and time pressure can make it hard to identify the relevant cues. Ozel (1994a, b) indicates that cue recognition can be particularly a problem in complex environments such as hotel/casino occupancies, where the overload of environmental information is even more exasperated by time pressure. Therefore, considering the degree of time pressure and stress during ®res, relevant exit cues must be clearly perceivable and easily available. 6. Time pressure, stress and cue utilization during emergency egress The concept of range of cue utilization has been applied to dierent areas in the past, such as degrees of continuity of learning, latent learning by Bruner et al. (1955), and the organization of behavior and emotion by Easterbrook (1959). In general, the range of cue utilization is de®ned to be the total number of environmental cues in any situation an organism observes, maintains an orientation towards, responds to, or associates with a response. The latter also argues that ``emotional arousal acts consistently to reduce the range of cues that an organism uses''. This reduction can not only be attributed to stress, but also to the coping mechanisms such as ®ltration and acceleration used as a result of time pressure. A reduction in the range of cue utilization is said to have happened when the use of peripheral (occasionally or partially relevant) cues has been reduced, although the use of central and immediately relevant cues has been maintained (Bursill, 1953). At the early stages of a ®re incident, this can in fact work to the advantage of an
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occupant and is an indication of vigilant information processing. It is when time pressure and stress reduce the range of cue utilization to such a level that the occupant is not able to eectively function, that such a reduction can become a problem. It has been suggested that the reduction under stress in the range of cue utilization also represents a shrinkage of the perceptive ®eld (Bursill, 1953; Granger, 1953). Granger (1953) cites nine clinical references to the restriction of visual ®elds in anxiety. In ®re situations, only a mere 7±8% of people reported noticing exit signage during emergency egressing (Bryan, 1981). If peripheral cues are eliminated in a visual motor task, then the location of signage in the visual ®eld can play a very important role in its eective usage. The current practice in locating exit signage in buildings and their location in the perceptual ®eld of the occupants need to be further investigated. In discussing the use of luminous markers along egress routes, Krokeide (1988) indicates that ``For some reason, the ability to see important objects (marked with luminous material) clearly, and for instance to walk along a luminous stripe, inspires more con®dence than does dim general lighting. The eye is drawn to luminous parts and. . .guidance is found without frantic searching.'' Clearly in this case, the dimensions of the environment is reduced only to a handful of cues that are immediately relevant to the problem at hand, which is achieved by illuminating or marking them. Therefore, people process a much smaller set of cues than they would have to without such marking. This is consistent with the literature which indicates that a reduction in the range of cue utilization occurs under stress and that people utilize the available information through a ®ltering mechanism when they are under time pressure. Any precautions that help to reduce this range to only immediately relevant cues can facilitate better way ®nding under time pressure and stress. Direct cues regarding the emergency condition, such as audio warnings through a paging system or the broadcast of local short messages providing directional assistance can also be helpful to the degree that they are perceived as providing immediately relevant cues. The destructive eects of stress would be expected to occur only when the actual range of cue utilization falls below that which is required for the task. In testing the use of cues in perceptual tasks, it is suggested that one can disintegrate cues by reducing the physical dierences between the discriminanda, i.e. lowering illumination, lowering visibility, reducing exposure time to environmental cues, etc. In ®re and smoke conditions in a building, these are exactly the factors that disintegrate cues. Besides the obvious factors such as smoke and reduced exposure time to cues, the nature of the building can also aect the range of cue utilization. By reducing the physical dierence between discriminanda, i.e. by creating uniform interiors with little physical dierentiation, the use of cues that contribute to a more ecient way ®nding behavior can be greatly reduced. Broadhurst (1957) reviews additional evidence for the Yerkes±Dodson law, which suggests that the optimum intensity of drive falls with diculty of discrimination. This suggests that the more uniform the building interiors are, and also keeping in mind the potential smoke levels during a ®re event, the harder it will be to discriminate between environmental cues. This, in turn, might aect the drive level of the individual, and the potential for inaction and the likelihood of defensive avoidance may increase.
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Therefore, there is clearly a need to further research how drive levels of individuals are eected during emergency egress by buildings where ¯oor plans are repetitive, i.e. where it is hard to distinguish which ¯oor one is on; where all doors, including the doors to the protected exits are similarly designed; and where the color and the material of the doors make it hard to distinguish them from the surrounding wall surfaces. 7. Conclusions This research paper was clearly aimed at identifying relevant research questions on how people process environmental information for exiting under time pressure and stress in ®res. It strives to raise questions, rather than to provide answers. Possible distortions in the decision making capacity of an individual have never been considered within the context of eective decision making and exiting during ®re emergencies. Some of the research questions that emerged in this article can be summarized as: 1. How does the degree of vigilance in information processing aect emergency egress behavior? What are some possible methods of measuring the ``degree of vigilance'' in cue utilization? 2. How can one operationally de®ne what ``erratic emergency egress behavior'' is? What are some ways of measuring such behavior? Can ``distortions in the information processing capacity of the individual'' provide the framework for such a de®nition? 3. Can some of these distortions be as a result of: The impact of negative associations created by ®re exit signage on egress behavior and route selection process during ®res? The reduction in the range of cues utilized under time pressure in emergency exiting? Is there possibly a reduction in the perceptual ®eld as suggested by some researchers? If so, how does it aect the location of exit signage? The design of buildings and their eect on the drive levels of people during emergency exiting? How would reducing the physical dierence between discriminanda, such as creating uniform interiors, repetitive ¯oor plans, etc., and the introduction of smoke aect the drive levels of occupants during way ®nding under emergency conditions? The accentuation of the subjectively meaningful areas of a building during emergency egressing? How can one identify such spaces for dierent occupant groups? Could training or proper building design help to alleviate the problem? 4. How can one facilitate more eective emergency egress behavior? Is reduction of inter-response times between cues by lengthening perceptual access and by providing continuous and immediately relevant cues one possible method for this?
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5. What are the individual dierences in the information processing capacity of people in ®res, especially for speci®c age groups such as elderly and children? How does one measure such dierences? What role do time pressure and stress play in these individual dierences? These clearly indicate the need for more extensive studies on the role time pressure and stress can play on the total decision making process during ®res and on cue utilization during emergency exiting. They also point to the need for the development of eective research methods in these areas. Developing operational de®nitions for the distortions in the decision making capacity of the individual and identifying the methods with which such distortions can be measured are crucially important. In fact, these will have to be a major component of any future research undertaken to investigate the questions raised here. References Ben Zur, H., Breznitz, J.S., 1981. The eect of time pressure on risky choice behavior. Acta Psychologica 47, 89±104. Bickman, L., Edelman, P., McDaniel, M., 1977. A Model of Human Behavior in a Fire Emergency, NBSGCR-78-120. National Bureau of Standards, Center for Fire Research, Washington, DC. Broadhurst, P.L., 1957. Emotionality and the Yerkes±Dodson law. Journal of Psychol. 54, 345±352. Brown, R., 1965. Social Psychology. Free Press, New York. Bruner, J.S., Matter, J., Papanek, M.L., 1955. Breadth of learning as a function of drive level and mechanization. Psychol. Rev. 62, 1±10. Bryan, J., 1981. Implications for codes and behavioral models from the analysis of behavior response patterns in ®re situations as selected from the project people II study programs. Un. of Maryland, Dept. of Fire Protection, College Park, MD. Bursill, A.E., 1958. The restriction of peripheral vision during exposure to hot and humid conditions. Quart. J. Exp. Psychol. 10, 113±129. Canter, D., Breaux, J., Sime, J., 1980. Domestic, multiple-occupancy and hospital ®res. In: Canter, D. (Ed.), Human Behavior in Fire. Wiley and Sons, Chichester, pp. 117±136. Chertko, J.M., Kushigian, R.H., 1999. Don't Panic: the Psychology of Emergency Egress and Ingress. Praeger, CT. Easterbrook, J.A., 1959. The eect of emotion on cue utilization and the organization of behavior. Journal of Applied Psychology. Institute of Psychiatry, Un. of London. Granger, G.W., 1953. Personality and visual perception: a revision. Journal of Mental Science 99, 8±43. Janis, I.L., Mann, L., 1977. Decision Making: a Psychological Analysis of Con¯ict, Choice and Commitment. Free Press, New York, pp. 49. Kelley, H.H., Condry Jr., J.C., Dahlke, A.E., Hill, A.H., 1965. Collective behavior in a simulated panic situation. Journal of Experimental Social Psychology 1, 20±54. Krokeide, G., 1988. An introduction to luminous escape systems. In: Sime, J., Spon, E., Spon, F.N. (Eds.), Safety in the Built Environment. pp. 134±146. Miller, J.G., 1960. Information input overload and psychopathology. American Journal of Psychiatry 116, 695±704. Mintz, A., 1951. Non-adaptive group behavior. Journal of Abnormal and Social Psychology 46, 150±159. Montgomery, H., Svenson, O., 1989. Process and Structure in Human Decision Making. Wiley and Sons, Chichester, England, New York. Ozel, F., Weisman, G., 1984. Way ®nding, cognitive mapping and ®re safety: some directions for research and practice. Paper presented at the Environmental Design Research Institute Conference, California.
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Ozel, F., 1994a. Computer simulation of human behavior in spaces. In: Marans, R., Stokols, D. (Eds.), Environmental Simulation. Plenum Publishing. Ozel, F., 1994b. Cognitive factors that aect emergency egress in hotel/casino occupancies. In: Proceedings of the Environments for Tourism Conference, Las Vegas, NV. Ozel, F., Brown, J., Sambolin, G., 1997. Emergency egress in library buildings, article presented at the Southwest Regional Conference of the Association for Collegiate Schools of Architecture (ACSA), and published in the ACSA Working Papers. Passini, R., 1984. Way®nding in Architecture. Van Nostrand Reinhold, New York, NY. Proulx, G., 1993. A stress model for people facing a ®re. Journal of Environmental Psychology 13 (2), 137±147. Ranyard, R., Croizer, R.W., Svenson, O. (Eds.), 1997. Decision Making: Cognitive Models and Explanations. Routledge, London, New York. Sime, J., 1983. Aliative behavior during escape to exits. Journal of Environmental Psychology 3 (1), 21±41. Sime, J., 1985. Movement toward the familiar: person and place aliation in a ®re entrapment setting. Environment and Behavior 17 (6), 697±724. Simon, H.A., 1960. The New Science of Management Decision. Harper Publishing, New York. Sixsmith, X. et al., 1988. When is a door not a door? A study of evacuation route identi®cation in a large shopping mall. In: Sime, J., Spon, E., Spon, F.N. (Eds.), Safety in the Built Environment. pp. 62±74. Svenson, O., Maule, J.A., 1993. Time Pressure and Stress in Human Judgement and Decision Making, New York, NY: Plenum Press, pp. 18. Weisman, G.D., 1979. Way Finding in Buildings, PhD Dissertation, University of Michigan, College of Architecture and Planning, Ann Arbor, MI. Wood, G.P., 1979. Behavior Under Stress: People in Fires. Doctoral Dissertation, Loughborough University of Technology, UK. Wright, P., 1974. The harassed decision maker: time pressure, distractions and the use of evidence. Journal of Applied Psychology 59 (5), 555±561.
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Time pressure and stress as a factor during emergency egress F. Ozel College of Architecture and Environmental Design, Arizona State University, Tempe, AZ 85287-1605, USA
Abstract While human beings, as information processing entities, use environmental cues during route selection in ®re emergencies, time pressure, i.e. the limited time available to people, and the stress created by the physical threat of ®re, can aect how they process environmental information. This study focuses on theories on decision making under time pressure and stress, and applies them to the area of emergency egress and route selection during ®res. Narrowing of the range of cues attended to under time pressure, the emphasis placed on the negative aspects of decision alternatives and ®ltering of information are some of the examples of distortions in the information processing capacity of the individual. Spatial behavior greatly relies on how environmental information is utilized, and therefore any miscalculations in the use of this information can lead to ineective spatial, thus exiting, behavior. Furthermore, while some degree of stress can lead to a bene®cial vigilance in information processing, further increase in stress can create a hypervigilant state, limiting the capacity of the individual to process environmental information eectively. The article also provides examples from investigative reports of ®res to further discuss the topics addressed. # 2001 Elsevier Science Ltd. All rights reserved. Keywords: Decision making; Time pressure; Stress; Emergency egress
1. Introduction Various situations in everyday life, as well as crises, require making decisions while pressed by deadlines. The individual equipped with limited information handling capacity tries to balance the desire to accurately choose options which ultimately maximize his/her bene®ts and the equally important need to reduce the cognitive strains of the given decision task (Ben Zur and Breznitz, 1981). The rate of information processing could increase due to the rise in the amount of data to be processed or due to the decrease in the time available for processing. Such an E-mail address: [email protected] (F. Ozel). 0925-7535/01/$ - see front matter # 2001 Elsevier Science Ltd. All rights reserved. PII: S0925-7535(00)00061-8
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increase in information load is de®ned to be the time pressure on the decision task at hand. Regardless of which de®nition is taken, it is clear that decision making during ®re emergencies is time pressured. The decision process during ®res is also aected by the emotional state of the person involved. While the time constraint in itself is enough to create stress, the existence of a physical and very real threat to one's life can add considerable stress and aect the decision making capacity of the individual. In fact, the characteristics of ®re emergencies have already been de®ned as stress inducing by a number of researchers (Wood, 1979; Proulx, 1993). Here, the term stress is used to indicate ``psychological stress designating unpleasant emotional states evoked by threatening environmental events or stimuli'' (Janis and Mann, 1977). Typically, decision-making models that are process oriented focus on psychological processes and how they evolve over time. Studies in this area are increasingly drawing on methods and theories from cognitive psychology (Ranyard et al., 1997). Among these models is the one developed by Janis and Mann (1977). The signi®cance of this model for emergency decision situations originates from the fact that it was ®rst developed for emergency decision tasks and then applied to more general decision conditions. The premise of Janis and Mann's theory is that human beings make decisions under contrasting conditions that determine whether the stress engendered by decisional con¯ict will facilitate or interfere with vigilant information processing. Vigilance ``results in thorough information search, unbiased assimilation of new information, and other characteristics of high quality decision making'' (Janis and Mann, 1977). The degree of stress during an emergency determines how vigilant a person is in processing information regarding the emergency situation. This model is compatible with Simon's (1960) analysis of the role of motivation and emotion in controlling cognitive behavior, where human being is de®ned as a ``serial information processor''. Both of these approaches are in-line with the premise that human beings are information processing entities, and distortions in the capacity to process information can have an impact on the decisions made. This premise is also relevant for decisions made by occupants in ®re emergencies. The behavior of people in ®res is a total decision-making process where the circumstances created by ®re and smoke can modify, distort and change the mechanisms by which people make decisions. These distortions are primarily due to the limited time available for decision making while the stress created by the physical threat to life also becomes a major factor. 2. Decision making during ®res Many ®re safety researchers (Canter et al., 1980; Bryan, 1981) de®ne human behavior in ®res to be episodic in nature, where occupants display a variety of action sequences. Usually each episode has an identi®able goal and a number of observable actions associated with this goal (Ozel, 1994). While the sequence of the decision processes in ®re emergencies is important, action plans regarding the execution of each individual episode are equally important. For example, the decision to alert
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others must be complemented by an implementation plan, or the decision to exit requires that an exit be selected for exiting. Thus, while goals such as ®ghting the ®re, evacuating, investigating, etc., represent decision making as transitions from one episode to another, what implementation strategies to use represents decision making within an individual episode. Decision making within an episode as well as between episodes can be aected by less-than-ideal or not-optimally-vigilant (Janis and Mann, 1977) strategies people use in information processing due to time pressure and stress (Fig. 1). In the stress model developed by Proulx (1993), decision making in emergencies is de®ned in terms of the emotional stages users can experience. She argues that additional information provided during an emergency can serve to reduce the negative eects of stress and motivate evacuation behavior. Proulx (1993, p. 138) also recognises the ``ambiguous, incomplete and unusual nature of the information on which to base the decision making process'', especially at the early stages of a ®re emergency. Thus, the researcher primarily focuses on the nature of the information that is available at each stage of the decision process. This is important in complementing the theory that de®nes humans as ``information processing entities'' during emergencies. On the other hand, by studying the distortions in the decision making mechanisms, other researchers such as Janis and Mann (1977) and Miller (1960) direct their attention to the internal decision making mechanisms. This also represents the basic premise of this study, which states that given the same set of information, people may attend to information dierently depending on the degree of stress and the amount of time pressure they experience. Among the theories that concentrate on the internal decision mechanisms, Svenson and Maule (1993) introduce the theory of Dierentiation and Consolidation where decision making is regarded as an active process that allows the gradual differentiation of one alternative from others until it is ®nally chosen. In this model there is a strong distinction between the processes at the pre-decision phase verses the post-decision phase. The changing nature of the conditions during a ®re emergency
Fig. 1. Decision making under time pressure and the episodic nature of human behavior during ®res.
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can minimize the distinction between pre- and post-decision phases. As soon as an occupant makes a decision and starts to implement it, conditions might change, forcing the occupant to reassess the situation and make a new decision. Occupants are rarely committed to a single decision during a ®re emergency, as evidenced by behavioral episodes (Bryan, 1981). Therefore, while the occupant continues to re-assess his/her current goal to see if there is a need to change it (pre-decision phase), he/she also continues to process other relevant information in order to execute the current decision at hand (post-decision). Therefore, decisions are layered over each other, with pre and post phases continuously overlapping. Proulx (1993) also recognizes the overlapping nature of the decision processes in ®res, where episodes are represented in a spiral form, each level representing a certain degree of stress reached which then blends in with the next phase of the decision process. In the past, the eects of stress and time pressure on group behavior or social behavior have also been considered as a factor in decision making in ®res. This literature generally tends to focus on crowd behavior, emphasizing competitive verses cooperative behavior during exiting. Among these, Sime (1983) and Chertko and Kushigian (1999) summarize many of the theories (such as by Mintz, 1951; Brown, 1965; Kelley et al., 1965, etc.) on crowd behavior while focusing on the tradeos between the individual's objective thinking as opposed to his/her behavior based on his/her expectations of the behavior of the others in the crowd. The role of stress and time pressure in crowd behavior is out of the scope of the present study, since the focus here is primarily on exit behavior, cue utilization and the individual's information processing capacity under time pressure and stress. 3. Information processing under time pressure and stress Among the internal processes that modify and distort decision making under time pressure and stress are coping mechanisms which determine how available information is processed, and bolstering mechanisms which can directly act on the nature of the decisions made by changing the desirability of a decision in the positive direction and by limiting the objective use of the information that is attended to. 3.1. Coping mechanisms Miller (1960) argues that during decision making under time pressure, people use a number of coping mechanisms such as: 1. acceleration, which is the processing of information at a faster rate; 2. the avoidance of decision, which may express itself in random choices or making choices according to momentary standing out characteristics of choice alternatives; and 3. ®ltration, which can be viewed as a compromise strategy, where only subjectively important data are chosen for consideration, to cope with time pressured and unavoidable conditions.
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These mechanisms actually reduce the time pressure, and enable the decision maker to decide in a relatively consistent and organized way. They are more likely to be used when the threat of possible negative outcomes is stronger than the threat of not considering all information. In simplifying as proposed, a decision maker accepts some distortion in his or her subjectively ideal judgment policy. 3.2. Bolstering Montgomery and Svenson (1989) argues that decisions are governed by the desire to choose an alternative that is better at least in one attribute and equally good as all others. To achieve this, people tend to restructure the information about a decision problem in the desired direction of the dominance of one alternative. This is called ``bolstering'' and Janis and Mann (1977) also identify ``bolstering'' as a mechanism in ``defensive avoidance'' process when a decisional con¯ict exists. Whenever there is diculty in reaching a decision due to con¯icting decision alternatives, the occupant can use bolstering mechanisms where, rather than objectively weighting dierent alternative decisions during a ®re emergency, they might restructure the information in the direction of a desired decision. For example, once the decision to exit is made, exit choice decision can be bolstered in favor of one alternative over others. On the other hand, bolstering can also happen between episodes by favoring one course of action over other possible courses of action, such as preferring to investigate the ®re rather than deciding to exit, indicating defensive avoidance through bolstering. 4. A model for decision making in ®re emergencies Janis and Mann (1977) identify four dierent phases for decision making depending on the level of stress for any single decision. These mechanisms need to be re-examined within the context of the episodic nature of human behavior in ®res and the coping mechanisms used. While Proulx (1993) de®nes the levels of stress in terms of their potential eect on the emotional state of the individual (levels are: control, uncertainty, fear, worry, confusion) as well as the nature of the information such as whether it is irrelevant, task-relevant or ambiguous, Janis and Mann de®ne the stages of the decision making under stress in terms of the level of vigilance with which information is processed. Since the latter primarily focuses on the processes that are internal to the individual, it was seen as more applicable to the concepts investigated here and thus was further examined. 4.1. Uncon¯icted inertia Where the credibility of the initial source of information is assessed to see if the environmental cues indicate the existence of an immediate threat that might impact the occupant's welfare. At this point the occupant might rightfully or mistakenly choose to ignore the evidence and ignore the threat. At the beginning of the ®rst
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episode of behavior, an occupant might be at this phase, ignoring ®re alarms or unusual cues such as noise in the corridor. This can also be attributed to defensive avoidance where the occupant refuses to pay attention to the initial cues due to multiple coping mechanisms. The real danger of uncon¯icted inertia is that the occupant might loose too much time, leaving little time for further action. This can increase the potential for high time pressure further down the line. At this stage (®rst loop in her model), Proulx (1993) primarily attributes defensive avoidance to the ambiguous nature of the information, which can in fact be an important factor. 4.2. Uncon¯icted change Where the occupant starts to believe the existence of a threat and becomes more emotionally aroused. At this point, since the occupant is still under the belief that there is time to escape or the threat is not serious enough to pose a real danger, the level of stress or time pressure is not high enough to create real distortions in the information capacity of the individual. Nevertheless the occupant starts becoming more vigilant. The level of stress at this point completely depends on the background of the occupant and the speed with which the conditions deteriorate in the building. At this level, an occupant may go through several episodes of behavior, and the sequence of decisions can be impacted by the desire to ®nd the most appropriate course of action before the decision to exit is made (Fig. 2). 4.3. Defensive avoidance As the person's level of stress becomes more intense, distortions in the decisionmaking capacity can increase. At this point, the occupant also becomes aware that the time is running out, and thus time pressure starts taking its toll on the person's capacity to process information. This is probably the most likely point where the decision to exit will be made, if not already made by the occupant. At this point, one can expect to see an increase in the use of coping mechanisms such as ®ltering, paying attention to the negative dimensions of the situation, accelerated processing of information, bolstering etc. Or the occupant may choose to ``pass the buck'' to someone else for decision making, for example, by joining to a group or a person he/ she is aliated with and allowing others to make the decisions for him/her. At this
Fig. 2. Behavioral episodes and stages of vigilance. The numbers for the episodes are only for demonstration purposes, since the total number of episodes can vary depending on the individual circumstances. Not all of the stages of vigilance will be experienced by all people.
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point, aliation may play an important role, as evidenced by the aliation models of behavior in ®res (Sime, 1983). 4.4. Hypervigilance As long as the occupant maintains the belief that he/she can still reach safety, vigilant tendencies will remain active. But as the situation gets more and more hopeless and the occupant tries to execute his/her decision to egress, the stress level increases even further with very high levels of time pressure. Janis and Mann (1977) identify the most extreme case of hypervigilance as ``panic'', which has often been incorrectly depicted in the popular media as the ``typical'' mode of behavior in ®res. Hypervigilance is evidenced by the use of intense ®ltering of information at highly accelerated rates of processing. Such high levels of coping mechanisms can ultimately lead to errors in decision making. Since usually by this time in the decision sequence, the occupant is committed to exiting, distortions in information processing are more likely to impact the implementation of the ``Egress'' episode. In the literature that investigates ``panic'' in ®res, many researchers assert that behavior identi®ed as ``panic'' with hindsight can be seen as a perfectly appropriate behavior when the individual's speci®c circumstances during a ®re incident are investigated. In fact, Sime (1983, p. 22) states that the scienti®c validity of the concept of panic in a ®re context has been in serious contention in recent discussions, and thus brings no operational de®nition. Although dicult to bring an operational de®nition, the concept of panic has been investigated for individuals as well as for groups (Sime, 1983) and crowds (Chertko and Kushigian, 1999) in ®re situations. Sime points out that the traditional ``panic model'' assumes that individuals that belong to homogeneous populations compete with each other for limited exits, whereas ``aliative model'' asserts that people attempt to escape in groups of two or more implying a more cooperative rather than a competitive model for exiting. On the other hand, Chertko and Kushigian (1999) provide a discussion of dierent theories on ``panic'' behavior for crowds and for groups with less group cohesion, and recount six major ®res in terms of crowd behavior. The intention here is not to discuss dierent theories on ``panic'' behavior, but to identify potential areas that can complement such theories by looking at the distortions in the information processing capacity of the individual as a possible factor in erratic egress behavior, often incorrectly attributed to panic. Among such distortions is the possibility of people ``not attending to all relevant information'' either due to ®ltration process or due to the accelerated rate of information processing, in spite of the ready availability of such information. Thus, in some cases, the behavior termed ``panic'' can be explained by how people make decisions under time pressured conditions. For example, rushing to a familiar exit, or to a lobby exit; or going to a friend's room instead of directly exiting can be explained by how people ®lter information under time pressure ``by attending to more subjectively signi®cant data''. How much erratic decisions can be attributed to bolstering rather than to panic must also be studied both within and between episodes, since bolstering is de®ned as one of the mechanisms for defensive avoidance.
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Obviously, it is also necessary to investigate ``hypervigilance'' as a possible internal reason for behavior that is considered (with hindsight) inconsistent with rational behavior. 5. Time pressure and spatial behavior As discussed earlier, when an occupant is in a hypervigilant state, it is very likely that they are also trying to evacuate the building (Fig. 2). Therefore, one can expect to ®nd the distortions in the information processing capacity of the individual to impact exit behavior and thus spatial behavior the most. Information coming from environmental cognition literature suggests that spatial behavior is largely eected by the nature of the physical environment around us. In the past, several researchers (Weisman, 1979; Ozel and Weisman, 1984; Passini, 1984) have successfully argued that a physical environment, by virtue of its inherent characteristics, such as the degree of perceptual access, the degree of dierentiation, general con®guration, etc., aects way ®nding and spatial behavior of its occupants under emergency (Ozel, 1994a,b; Ozel et al., 1997) and non-emergency conditions. De®ciencies in processing environmental information due to time pressure and stress can have profound eects on spatial behavior. When a decision maker attends to certain dimensions only due to a ®ltration process, these dimensions consequently have greater impact on his/her judgments than they normally would. There is some data that supports the theory that people attend to negative dimensions more when under time pressure. If he/she focuses on negative evidence, the person sacri®ces awareness of the extent of positive outcomes to be expected, and vice versa. In the context of decision making under certainty, Wright (1974) found that time pressure caused attribution of more weight to negative information in purchase options. Later Ben Zur and Bretnitz (1981) found similar results in an investigation of decision making under risk. Under time pressure conditions, choices were less risky and a tendency for preferring negative dimensions was also found. This argument has some important implications on exit choice behavior in ®res. There is some evidence in the ®re safety literature that people prefer more familiar routes during ®re incidences (Sime, 1983, 1985). This ®nding is also in-line with the theory on cognitive mapping and spatial behavior. The preference for familiar exits becomes understandable when such routes are immediately available to the cognition of the individual and thus perceived to be the less risky choice, since any other route will have an additional risk factor of losing one's way and not being able to spot the exact location of the alternate exit. Therefore, with the introduction of time pressure and stress, preference for familiar exits is further emphasized. Negative associations with a particular route have in the past led some people to prefer other exit routes. In one such case, in a nursing home ®re (Bickman et al., 1977), three out of four exits were labeled with signs indicating that they should only be used in case of emergency and that an alarm will sound when used. Furthermore, patients were penalized by the nurses if they used these exits during daily functioning
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of the building. During an actual ®re incident, only six out of more than 100 residents used the three peripheral exits with negative labeling and thus negative associations, although many of them later indicated that they knew the location of these exits. Occupants who were interviewed after the ®re incident indicated that the use of these doors were prohibited. Under the pressure of time and stress people were not able to concentrate on the positive aspects of alternative routes, such as closeness to the present location of the occupant, not having to go through the ®re area, less crowding, etc., but used the negative implications instead. Therefore, by prohibiting the use of alternate exits during non-emergency conditions, we can not only limit the formation of cognitive maps, but can also inadvertently create negative associations and biases, highly limiting the likelihood of their use in emergencies. Training and education can help to reduce the problem of attending to the negative dimensions of an emergency situation, and to increase the ability to pay attention to relevant cues for decision making. In discussing ®re exit doors with murals on them in a shopping mall, Sixsmith et al. (1988) argue that ``Given that way ®nding has to be quick and ecient in the event of a ®re, . . .®re doors should be readily recognizable. . .''. Thus, the ®ltration of cues is identi®ed as a problem in exit recognition, indicating that ®re doors must provide unambigious cues due to the speed of information processing needed under such conditions (i.e. time pressure), possibly distorting or delaying people's perception of relevant cues. Although this is clearly an extreme case where cues were hidden by murals, in a complex environment such as a shopping mall the overload of environmental cues (store windows, lighting, etc.) and time pressure can make it hard to identify the relevant cues. Ozel (1994a, b) indicates that cue recognition can be particularly a problem in complex environments such as hotel/casino occupancies, where the overload of environmental information is even more exasperated by time pressure. Therefore, considering the degree of time pressure and stress during ®res, relevant exit cues must be clearly perceivable and easily available. 6. Time pressure, stress and cue utilization during emergency egress The concept of range of cue utilization has been applied to dierent areas in the past, such as degrees of continuity of learning, latent learning by Bruner et al. (1955), and the organization of behavior and emotion by Easterbrook (1959). In general, the range of cue utilization is de®ned to be the total number of environmental cues in any situation an organism observes, maintains an orientation towards, responds to, or associates with a response. The latter also argues that ``emotional arousal acts consistently to reduce the range of cues that an organism uses''. This reduction can not only be attributed to stress, but also to the coping mechanisms such as ®ltration and acceleration used as a result of time pressure. A reduction in the range of cue utilization is said to have happened when the use of peripheral (occasionally or partially relevant) cues has been reduced, although the use of central and immediately relevant cues has been maintained (Bursill, 1953). At the early stages of a ®re incident, this can in fact work to the advantage of an
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occupant and is an indication of vigilant information processing. It is when time pressure and stress reduce the range of cue utilization to such a level that the occupant is not able to eectively function, that such a reduction can become a problem. It has been suggested that the reduction under stress in the range of cue utilization also represents a shrinkage of the perceptive ®eld (Bursill, 1953; Granger, 1953). Granger (1953) cites nine clinical references to the restriction of visual ®elds in anxiety. In ®re situations, only a mere 7±8% of people reported noticing exit signage during emergency egressing (Bryan, 1981). If peripheral cues are eliminated in a visual motor task, then the location of signage in the visual ®eld can play a very important role in its eective usage. The current practice in locating exit signage in buildings and their location in the perceptual ®eld of the occupants need to be further investigated. In discussing the use of luminous markers along egress routes, Krokeide (1988) indicates that ``For some reason, the ability to see important objects (marked with luminous material) clearly, and for instance to walk along a luminous stripe, inspires more con®dence than does dim general lighting. The eye is drawn to luminous parts and. . .guidance is found without frantic searching.'' Clearly in this case, the dimensions of the environment is reduced only to a handful of cues that are immediately relevant to the problem at hand, which is achieved by illuminating or marking them. Therefore, people process a much smaller set of cues than they would have to without such marking. This is consistent with the literature which indicates that a reduction in the range of cue utilization occurs under stress and that people utilize the available information through a ®ltering mechanism when they are under time pressure. Any precautions that help to reduce this range to only immediately relevant cues can facilitate better way ®nding under time pressure and stress. Direct cues regarding the emergency condition, such as audio warnings through a paging system or the broadcast of local short messages providing directional assistance can also be helpful to the degree that they are perceived as providing immediately relevant cues. The destructive eects of stress would be expected to occur only when the actual range of cue utilization falls below that which is required for the task. In testing the use of cues in perceptual tasks, it is suggested that one can disintegrate cues by reducing the physical dierences between the discriminanda, i.e. lowering illumination, lowering visibility, reducing exposure time to environmental cues, etc. In ®re and smoke conditions in a building, these are exactly the factors that disintegrate cues. Besides the obvious factors such as smoke and reduced exposure time to cues, the nature of the building can also aect the range of cue utilization. By reducing the physical dierence between discriminanda, i.e. by creating uniform interiors with little physical dierentiation, the use of cues that contribute to a more ecient way ®nding behavior can be greatly reduced. Broadhurst (1957) reviews additional evidence for the Yerkes±Dodson law, which suggests that the optimum intensity of drive falls with diculty of discrimination. This suggests that the more uniform the building interiors are, and also keeping in mind the potential smoke levels during a ®re event, the harder it will be to discriminate between environmental cues. This, in turn, might aect the drive level of the individual, and the potential for inaction and the likelihood of defensive avoidance may increase.
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Therefore, there is clearly a need to further research how drive levels of individuals are eected during emergency egress by buildings where ¯oor plans are repetitive, i.e. where it is hard to distinguish which ¯oor one is on; where all doors, including the doors to the protected exits are similarly designed; and where the color and the material of the doors make it hard to distinguish them from the surrounding wall surfaces. 7. Conclusions This research paper was clearly aimed at identifying relevant research questions on how people process environmental information for exiting under time pressure and stress in ®res. It strives to raise questions, rather than to provide answers. Possible distortions in the decision making capacity of an individual have never been considered within the context of eective decision making and exiting during ®re emergencies. Some of the research questions that emerged in this article can be summarized as: 1. How does the degree of vigilance in information processing aect emergency egress behavior? What are some possible methods of measuring the ``degree of vigilance'' in cue utilization? 2. How can one operationally de®ne what ``erratic emergency egress behavior'' is? What are some ways of measuring such behavior? Can ``distortions in the information processing capacity of the individual'' provide the framework for such a de®nition? 3. Can some of these distortions be as a result of: The impact of negative associations created by ®re exit signage on egress behavior and route selection process during ®res? The reduction in the range of cues utilized under time pressure in emergency exiting? Is there possibly a reduction in the perceptual ®eld as suggested by some researchers? If so, how does it aect the location of exit signage? The design of buildings and their eect on the drive levels of people during emergency exiting? How would reducing the physical dierence between discriminanda, such as creating uniform interiors, repetitive ¯oor plans, etc., and the introduction of smoke aect the drive levels of occupants during way ®nding under emergency conditions? The accentuation of the subjectively meaningful areas of a building during emergency egressing? How can one identify such spaces for dierent occupant groups? Could training or proper building design help to alleviate the problem? 4. How can one facilitate more eective emergency egress behavior? Is reduction of inter-response times between cues by lengthening perceptual access and by providing continuous and immediately relevant cues one possible method for this?
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5. What are the individual dierences in the information processing capacity of people in ®res, especially for speci®c age groups such as elderly and children? How does one measure such dierences? What role do time pressure and stress play in these individual dierences? These clearly indicate the need for more extensive studies on the role time pressure and stress can play on the total decision making process during ®res and on cue utilization during emergency exiting. They also point to the need for the development of eective research methods in these areas. Developing operational de®nitions for the distortions in the decision making capacity of the individual and identifying the methods with which such distortions can be measured are crucially important. In fact, these will have to be a major component of any future research undertaken to investigate the questions raised here. References Ben Zur, H., Breznitz, J.S., 1981. The eect of time pressure on risky choice behavior. Acta Psychologica 47, 89±104. Bickman, L., Edelman, P., McDaniel, M., 1977. A Model of Human Behavior in a Fire Emergency, NBSGCR-78-120. National Bureau of Standards, Center for Fire Research, Washington, DC. Broadhurst, P.L., 1957. Emotionality and the Yerkes±Dodson law. Journal of Psychol. 54, 345±352. Brown, R., 1965. Social Psychology. Free Press, New York. Bruner, J.S., Matter, J., Papanek, M.L., 1955. Breadth of learning as a function of drive level and mechanization. Psychol. Rev. 62, 1±10. Bryan, J., 1981. Implications for codes and behavioral models from the analysis of behavior response patterns in ®re situations as selected from the project people II study programs. Un. of Maryland, Dept. of Fire Protection, College Park, MD. Bursill, A.E., 1958. The restriction of peripheral vision during exposure to hot and humid conditions. Quart. J. Exp. Psychol. 10, 113±129. Canter, D., Breaux, J., Sime, J., 1980. Domestic, multiple-occupancy and hospital ®res. In: Canter, D. (Ed.), Human Behavior in Fire. Wiley and Sons, Chichester, pp. 117±136. Chertko, J.M., Kushigian, R.H., 1999. Don't Panic: the Psychology of Emergency Egress and Ingress. Praeger, CT. Easterbrook, J.A., 1959. The eect of emotion on cue utilization and the organization of behavior. Journal of Applied Psychology. Institute of Psychiatry, Un. of London. Granger, G.W., 1953. Personality and visual perception: a revision. Journal of Mental Science 99, 8±43. Janis, I.L., Mann, L., 1977. Decision Making: a Psychological Analysis of Con¯ict, Choice and Commitment. Free Press, New York, pp. 49. Kelley, H.H., Condry Jr., J.C., Dahlke, A.E., Hill, A.H., 1965. Collective behavior in a simulated panic situation. Journal of Experimental Social Psychology 1, 20±54. Krokeide, G., 1988. An introduction to luminous escape systems. In: Sime, J., Spon, E., Spon, F.N. (Eds.), Safety in the Built Environment. pp. 134±146. Miller, J.G., 1960. Information input overload and psychopathology. American Journal of Psychiatry 116, 695±704. Mintz, A., 1951. Non-adaptive group behavior. Journal of Abnormal and Social Psychology 46, 150±159. Montgomery, H., Svenson, O., 1989. Process and Structure in Human Decision Making. Wiley and Sons, Chichester, England, New York. Ozel, F., Weisman, G., 1984. Way ®nding, cognitive mapping and ®re safety: some directions for research and practice. Paper presented at the Environmental Design Research Institute Conference, California.
F. Ozel / Safety Science 38 (2001) 95±107
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Ozel, F., 1994a. Computer simulation of human behavior in spaces. In: Marans, R., Stokols, D. (Eds.), Environmental Simulation. Plenum Publishing. Ozel, F., 1994b. Cognitive factors that aect emergency egress in hotel/casino occupancies. In: Proceedings of the Environments for Tourism Conference, Las Vegas, NV. Ozel, F., Brown, J., Sambolin, G., 1997. Emergency egress in library buildings, article presented at the Southwest Regional Conference of the Association for Collegiate Schools of Architecture (ACSA), and published in the ACSA Working Papers. Passini, R., 1984. Way®nding in Architecture. Van Nostrand Reinhold, New York, NY. Proulx, G., 1993. A stress model for people facing a ®re. Journal of Environmental Psychology 13 (2), 137±147. Ranyard, R., Croizer, R.W., Svenson, O. (Eds.), 1997. Decision Making: Cognitive Models and Explanations. Routledge, London, New York. Sime, J., 1983. Aliative behavior during escape to exits. Journal of Environmental Psychology 3 (1), 21±41. Sime, J., 1985. Movement toward the familiar: person and place aliation in a ®re entrapment setting. Environment and Behavior 17 (6), 697±724. Simon, H.A., 1960. The New Science of Management Decision. Harper Publishing, New York. Sixsmith, X. et al., 1988. When is a door not a door? A study of evacuation route identi®cation in a large shopping mall. In: Sime, J., Spon, E., Spon, F.N. (Eds.), Safety in the Built Environment. pp. 62±74. Svenson, O., Maule, J.A., 1993. Time Pressure and Stress in Human Judgement and Decision Making, New York, NY: Plenum Press, pp. 18. Weisman, G.D., 1979. Way Finding in Buildings, PhD Dissertation, University of Michigan, College of Architecture and Planning, Ann Arbor, MI. Wood, G.P., 1979. Behavior Under Stress: People in Fires. Doctoral Dissertation, Loughborough University of Technology, UK. Wright, P., 1974. The harassed decision maker: time pressure, distractions and the use of evidence. Journal of Applied Psychology 59 (5), 555±561.