Trimpop_RiskHomeostasisTheory

8/12/2019 Trimpop_RiskHomeostasisTheory

1/12

PergamonSafety Science, Vol. 22, No. 1-3. pp. 119- 130, 1996

Copyright 0 1996 Elsevier Science LtdPrinted in Great Britain. All rights reserved

0925-7535/96 15.00 + 0.00

RISK HOMEOSTASIS THEORY PROBLEMS OFTHE PAST AND PROMISES FOR THE FUTURERfidiger M. TrimpopFriedrich Schiller University Jena Germany

Abstract-Risk homeostasis theory (RHT) has sparked continuous scientific debate for momthan a decade. Beginning with total rejection, it was then increasingly examined with doubtfulcuriosity. In the following years it received some support, until there is now universalacceptance of one of its key components, namely risk compensation or behavioural adaptation.The strict notion of risk homeostasis, however, is still open for debate, as some of its problems,both theoretical and empirical, have not been sufficiently resolved. For example, falsifying theconcept seems to be impossible in field studies, as not all possible behavioural adaptations canbe controlled for. Yet, while some aspects need to be clarified, RHT continues to sparkinteresting research and to provide useful ideas for accident reduction and preventing heahh-re-lated dangers, such as the focusing on incentives. Including the notion of risk-taking behaviouras being sometimes attractive and changing the notion of a single to that of multiple targetlevels of risk are among suggestions for theoretical development. Using participative methods tochange both risk assessment and the value of safety and health are suggestions for furtherapplications of RHT made in this paper. Copyright 0 1996 Elsevier Science Ltd

1 The development of risk homeostasis theory

Risk homeostasis theory @IIT) is based upon risk compensation theory (RCT), as Wildenamed his concept in his early publications. The basic notion is that of behavioural adaptationto compensate between perceived risk and desired risk. Although new in the area of safety andhealth, the concepts of compensation and homeostasis were used as early as 1859 inphysiology by Bernard, and then later by Cannon (1929, 1932) who coined the termhomeostasis in relation to bodily processes, such as blood pressure, temperature andrespiration rate, which all maintain an optimal level. Specific individual values exist for eachsituation and action, but on average body temperature can be described with a constant value,This process of fluctuation around a target level is called homeostusis. If one catches a coldthen temperature rises, if one goes jogging respiration and heart rate increase. The valuesfluctuate around a new, often higher level. When the situation changes, they return to the usualbase rate. Others have also described homeostatic processes. For example, Jungs (1954)compensation theory of personality and Lewins (1951) quasi-stationary equilibria both

119


2/12

12 R.M . Trimpop

refer to compensation behaviour and homeostatic fluctuations of a variable within certainboundaries.

An early study of the behavioural compensation process in traffic was that of Taylor (1964)who described driving as a self-paced task, governed by emotional tension and anxiety levels,which represent a transformation of physiological experiences of risk, which in turn influencethe driving task in a closed-loop feedback process. Taylor (1964, 1976) reported that at formeraccident spots drivers compensated behaviourally by adjusting risk levels to a subjectivelydesired level. Most likely, participants perceived some actual or possible danger at theaccident spot, and consequently, drove more cautiously in response to that, while their overallGSR (galvanic skin response) levels remained stable. This finding suggests that people canperceive signals about risky situations without conscious knowledge (also called precognitiveloops, Michon, 1989), and that drivers compensate with their behaviour (e.g. speeding,slowing down) for undesired levels of perceived risk. Heino et al. (1990) replicated Taylorsstudy and found support for risk homeostasis theory. Cownie and Calderwood (1966)formulated the compensation principle and showed in black spot treatment that technicalsafety features are rendered ineffective, as drivers employ a risk compensation feedback loop.They slowed down at the black spot, but compensated for the lost time by speedingafterwards. Similar findings were reported by Boyle and Wright (1987).

Wilde (1976, 1978) formalised this notion by designing a model of driver behaviour,namely risk compensation theory. The model is based on compensating actions, triggered by aperceived discrepancy between observed and desired levels of risk. Wilde (1982a) extendedthis concept to risk homeostasis arguing that instead of compensating for risk per se driverswould try to maintain a subjectively optima1 level of tolerated risk (rather than desired risk). Inhis risk homeostasis theory, Wilde (1982a) referred to a fluctuating level, which matches onlyon average a certain target level of risk. He distinguishes homeostasis from isostasis, the lattermeaning an invariate, constant level of risk, for which homeostasis is often mistaken.

Risk compensation and risk homeostasis function under the same general principles of aperception-evaluation process with feedback-regulated adjustment behaviour, under the influ-ence of individual capabilities and situational circumstances. For example, if people aredriving on a highway and it starts to rain or snow they will slow down to reduce the likelihoodof having an accident. If the sun comes out again, however, they will accelerate to a speed atwhich they feel comfortable, representing their target level of risk. According to Wilde(1985a, 1988a), externally introduced safety measures, such as seat-belts or anti-lock brakingsystems (ABS), can at best only reduce accidents until the consequences are perceived by thedriver. Once the increase in safety is noticed, the driver will feel safer and compensate for thisincrease in safety by transforming it into performance benefits, such as shorter travelling timeor higher comfort by paying less attention or other risk-taking behaviour.Wildes (1982a) solution to the seemingly impossible task of accident reduction lies inconcentrating on the target level of risk, rather than on technical solutions. As long as thesubjective experience of risk stays the same, motivation for compensation behaviour will alsoremain at the same level. The target level of risk depends on the perceived costs and benefitsof the safe and risky behavioural alternatives. These utilities are a function of economic, valueand person-related variables and their long- and short-term as well as momentary fluctuations(Wilde, 1986). To reduce accidents, Wilde (1985a) suggested increasing the value of cautiousbehaviour (e.g. incentives) and the negative consequences of risky behaviour (e.g. punish-ment), or decreasing the benefits of risky behaviour (e.g. heroism) or the negative conse-quences of cautious behaviour (e.g. time loss). As a result the target level of risk will drop. A


3/12

RHT : pm problems rend uture promises 121

lower target level of risk should lead to objectively less risky behaviour, such as slowerspeeds or higher levels of attention. Wilde (1982a, 1986) and Adams (1985) extended RHTfrom the domain of driving to other health-related lifestyles, such as smoking, overeating orAIDS, and suggested that RHT is universal, but that individual differences in target levels ofrisk exist.

2. Research on R T and RHTAlthough there is a conceptually very important difference between risk compensation and

homeostasis, namely that of partial versus full compensation, it can be argued that compensat-ing behaviour is a necessary but not sufficient requirement for homeostasis. Overall, uncon-trolled studies have shown strong support for risk compensation but only some evidence infavour of homeostasis, while controlled laboratory research and simulation studies haverevealed stronger support for the assumption of a homeostatic process related to risk-takingbehaviour.2.1. Research on RCT and RHT under uncontr ol l ed condi t i ons

Peltzman (1975) report that in spite of improved safety features, such as seat-belts,impenetrable windshields, dual braking systems and padded instrument panels, no reduction inthe accident rate per 1000 million vehicle miles occurred. Kunkel (1983) as well as Lund andWilliams (1985) review many publications on safety courses and traditional training andeducation programmes and found them to be not only ineffective, but sometimes evencounterproductive, as participants felt more competent afterwards and drove more danger-ously, thus compensating for their lowered perceived level of risk. Jonah et al. (1982) refer toan additional problem of self-selection, namely that drivers who participate in safety coursesare more safety conscious to begin with and that the increase in risk-taking after feeling morecompetent might even be higher for other road users. Jonah and Lawson (1984) and Jonah andDawson (1982) report that seat-belt use could be predicted from community and individualattitudes to mandatory laws, and that the effect of these laws fell far short of their predictedreductions on Canadian fatality and injury rates. Svenson et al. (1985) report that USAmerican and Swedish drivers overestimated both their driving abilities and driving safety.Thus, seat-belt use could not be infIuenced by advertisements about its effectiveness inreducing injuries, as overconfident drivers believe that they can avoid accidents, but could beinfluenced by presenting facts related to personal comfort and social norms. The significantdrop of about 40% in accidents after Sweden and Iceland switched from left-hand toright-hand traffic (N?&Znen and Summala, 1976) was taken as support for RCT. Due to theswitch, a higher level of risk was perceived, thus the drivers compensated by driving verycarefully, until they got used to the new situation. Over a period of one year Swedish accidentrates returned to the previous levels. In Iceland, with about one fortieth of the inhabitants, ittook only 2.5 months for the accident rate to return to its pre-switch level.

Ruppert (1994) report that the introduction of safer machinery in a company reduced thenumber of accidents among operating personnel, but increased the number and severity ofaccidents by maintenance staff.Pfafferott and Huguenin (1993) summarise the results of an OECD report (1990) onBehavioural Adaptations to Changes in the Road Transport System. They review empirical


4/12


5/12

RHT past problems and uture promises 123

control. They believed that ABS would give their cars better braking power under all roadconditions and also better steering. Many drivers (62%) stated that the ABS system makespeople take more risks and drive less cautiously. The authors found that accidents due toanother car cutting in before the ABS taxis were significantly reduced, while other accidents,especially in snowy conditions, rose. While ABS is promoted as a safety feature whichreduces accidents, the overall accident rate in this study showed a slight but not significantincrease for ABS taxis. The authors reasoned that the results can best be understood by RHT,since almost full compensation behaviour was assumed to have taken place.

Hoyes et al. (1992) found support for RHT in a simulated alarm-handling task in a nuclearpower plant control room. Jackson and Blackman (1994) showed in a between-within drivingsimulation study that an increase in speed limits and reduction of speeding fines led toincreased driving speed but had no effect on accidents, as predicted by RHT. Also, increasedaccidents costs caused large and significant reductions in accident frequency but no change inchoice of speed. The authors viewed their result as mainly supporting RHT, although completecompensation was not established. Simulations do suffer, however, from being withdrawnfrom the complexity of daily life and even if financial or social risks can be inducedsuccessfully, the experience of physical risks cannot be simulated for obvious ethicalreasons. Hoyes (1994) and Hoyes and Glendon (1993) discuss simulation research on RHT.They conclude that simulations allow for examination of personality factors, cognitive andpre-attentive processes, physiological and emotional responses, all of which cannot beestablished by analysing accident data or observations in the field (see also Trimpop, 1994b).

To summarise, while RHT receives some support from field studies and stronger support insimulation studies, some unresolved problems with the concept remain and will be discussednext.

3. Problems related to RHTA review of the literature reveals a heated debate on whether findings should be interpreted

in favour of or against RHT. The arguments are well documented in Hoyes and Glendon(1993), Adams (1988), Shannon (1986), Wilde (1985b), Evans (1985, 1986a,b 1991) McKenna(1985, 1987, 1988, 1990), Wilde (1982a, 1984) and Slavic and Fischhoff (1982). Here, someconceptual problems with RHT will be discussed.Cole and Stephen (1982) argue that there are considerable difficulties in transferringindividual motives and behaviours to a societal level. Orr (1982) points out the difficulty forthe individual of assessing probabilities of risk at the moment of decision-making, but Wilde(1982b) refers to delayed feedback, so that the individual driver constantly receives informa-tion through media, observations and by word of mouth to update personal risk assessments.

Lund and Zador (1984) find no differences in speed selection, stopping at amber, gapacceptance, and following distance after the introduction of seat belts. They conclude that riskcompensation or homeostasis did not occur and that seat belts will save many lives inNewfoundland. Wilde (1988a) argues, however, that the restriction in observations andbehaviours does not rule out the possibility of other behavioral changes (e.g. driving morerecklessly or less attentively) at other than the observed times, for example at night.Jamrssen and Tenkink (1988) argue that phenomena observed as supportive for RHT canalso be explained in a model of maximising utilities, disregarding risk completely. Theyincluded expected benefits and calculated the likely action for certain circumstances. As,


6/12

124 R.M . Trimpop

however, RHT also claims to be a utility theory, it could be further developed to include thepositive psycho-physiological experiences of risk, arousal, challenge and curiosity, as well asthe intrinsic rewards associated with them (Trimpop, 1994a), which so far have not beenaddressed in RHT.

Adams (1988), McKenna (1990) and Hoyes and Glendon (1993) refer to the difficulty ofdisproving RHT, since compensation behaviour for induced safety measures can fluctuate overtime and across activities. Laboratory studies can only control for certain behaviours and for alimited amount of time, while compensation can occur later or in different forms. Outside thelaboratory even more behavioural alternatives remain uncontrolled for. Also, as the compari-son between target risk and perceived risk is a subjective cognitive-emotional process, thequestion of whether risk homeostasis occurs can only be answered by people themselves andnot by analysing accidents.

Another problem resides within the notion of a single target level of risk. Trimpop (1994a)assessed the target level of risk by determining how far participants responses in atime-estimating task deviated from their optimal response pattern, thus showing a riskinclination or avoidance equivalent to the target risk. Data revealed that this target level of riskwas newly adjusted after every change in the probability of penalty, in the incentive, and evenafter a time-lag without change. Target levels started high and gradually approached anoptimal level of score maximisation, thus offering support for homeostasis, but not for anindividually constant target level of risk. Changes in an individuals target level may alsooccur over a life span, or may differ for financial versus physical risks (Trimpop, 1994a). Thisholds even more true for a population. Thus, target risks are an average accumulation ofmultiple target levels of risk and may thus reflect the norm or value of risk for an individual,or of the risk/safety culture of a society.A major shortcoming of RHT is its focus on undesired aspects of risk. Slavic and Fischhoff(1982) criticise RHT for not dealing adequately with the need for variety. The authorsclaimed that need for variety and homeostasis are counteractive, as the search for challenges,new experiences and risks cannot be explained by striving for a target level of risk, exceptafter a process of adaptation, with a resulting rise in the target level of risk. Risk, however, isnot only characterised by the notion of possible loss, but also by opportunities to gainsomething, which must also to be considered as an attractive motivating factor. People maytherefore strive for situations of uncertainty instead of avoiding them. Benefits of exposingoneself to risks are also regulated intrinsically, such as through hormones, feelings of pride,success, mastery (see risk motivation theory, Trimpop, 1990, 1994a). Risk-taking behaviourhas therefore - apart from undesired negative consequences such as fear - positiveconsequences such as physical enjoyment (sex, adrenaline high, thrill, etc.>, financial andsocial success (fame and fortune), and is also evolutionarily and developmentally necessary tocope with and to introduce changes in life (Trimpop, 1994a). So far, RHT has neglected theseaspects, although such attractive aspects of risk-taking behaviour in driving may be importantin explaining the occurrence of traffic accidents and for designing countermeasures.

4. Promises of RHT: influencing motivation to prevent accidentsRHT suggests two psychologically very different approaches to improve health and safety.One approach is rooted in the notion of behavioural adaptation to the perceived level of r iskwhile the other aims at changing motivational aspects of the target level of ri sk Both


7/12

RHT: past problems cmdfuture promises 125approaches should lead to changes in behaviour towards increasing safety and health, as eitherreal dangers are perceived more accurately instead of being underestimated, or the value ofsafe behaviour is increased and that of risky behaviour is decreased. An underlying assump-tion is that of reducing cognitive dissonance between behaviour and values (Festinger, 1957).If people behave safely for some time to gain benefits or to avoid costs, then their values,norms and beliefs may adjust accordingly. Alternatively, people will readjust their behaviourtowards their values, as it seems to be impossible to have dissociated values and behavioursfor extended periods of time.4.1. Changing the perceived level of risk in risk assessment

Musahl et al. (1992) report that coal miners perceived gangways in their mines withoutobstacles as not risky and those where walking was very difficult due to equipment anduneven terrain, as very risky. Accident data, however, showed the opposite. Where miners feltsafest they had the highest number of accidents. Musahl and Alslebens (1992) approach tochange the situation was to heighten awareness about real dangers by using safety circles,teaching sessions and media. Overall, Musahl et al. (1995) report accident reductions of about30%. Although the approach was based on the theory of learning rather than on RHT, thestudies illustrate behavioural changes responding to changes in the perception of risk(Trimpop, 1994c).4.1 .I. Economic fluctuations change the perceived costs of risk taking behaviour

Wilde (1991, 1994b) argues that the ups and downs of the economy strongly influencetraffic accident rates, as poor economic conditions lead to reduced accidents, both becausepeople drive less often and more carefully. Adams (1985) uses data collected by Partyka(1984) and reports determination coefficients of r = 0.88-0.95 between accidents and em-ployment statistics in Britain. Wilde (1994a) finds similarly high determination coefficientsbetween accidents and economic fluctuations, such as unemployment or wages for Germany(0.831, the Netherlands (0.88) and Canada (0.88). Wilde (1994a) argues that economic crisescan produce lower target levels of risk because they increase the relative costs of accidents,and the costs of risky joy-driving. This in turn, may reduce the target level of risk and with itmotivation for engaging in risk-taking behaviour. Financial gains at an individual level tochange risk-taking behaviour may be applied in industry and insurance companies throughincentive systems.4.12. Using incentives to improve safety

Wilde (1985a) cites a study conducted in a German branch of the Kraft Food Corporationwith a vehicle fleet of 600 trucks and vans. In 1957, drivers were told that they would receivea bonus of about DM 300 for every half year of driving without culpable accidents. In 1981,the culpable accident rate per kilometre driven was 14% of the 1957 rate (Wilde, 1985a),while the total accident rate per kilometre driven was 25% of the 1957 rate.

Fox et al. (1987) examine the effect of offering trading stamps for no lost-time injuries, noequipment damage due to accidents, for making adopted safety suggestions, and for prevent-ing an accident. Trading stamps were withdrawn when co-workers in the group were injuredor caused accidents with equipment damage. Long-term reductions in lost-time injuries andaccident related costs were found in both open-pit mines studied.


8/12

126 R.M . Trimpop

Harano and Hubert (1974) formed three matched groups of 9971 participants who receiveda promise of a one-year extension of their drivers licence without having to take the writtenexam if they stayed accident free in the next year. One group of matched participantsconstituted the no-treatment control group. The second group were those drivers whose licencerenewal was up in the forthcoming year. They showed a significant reduction in accidents(22%) compared with the control group. The accident rate of those drivers whose licencerenewal was coming up later (third group) remained unchanged. Especially effective was thetreatment for drivers below the age of 25, being the group with the highest proportion ofaccidents and the lowest income. In the following years their reduction in accidents was 33%before the experiment ended.

Siero et al. (1989) find similar results. More support for the effectiveness of incentives inaccident reduction has been reviewed by Wilde (1992; 1994c). Incentives have been shown tobe both highly and poorly effective in accident prevention. If they are installed withmanagerial commitment, proper communicative support, or acceptance in the target groupthen they tend to be effective, otherwise they are not (Wilde. 1992; Trimpop, 1994~~).

However, a theoretical question arises for RI-IT with using incentive plans as an externallyintroduced measure. Momentarily increased perceptions of risk may not influence the personslong-term target level of risk. The subjective level is held constant, as the newly introducedfinancial risk compensates for the reduced physical risk of incurring an accident. As long asthe added risk of losing or winning money is active it might change behaviour, but as soon asthe incentive plan stops, the behaviour might change back to become objectively more risky tomaintain the homeostatic balance. Thus, the same argument that RHT holds against externaltechnical changes might be made against external motivational changes, such as incentives,punishment, or praise. These considerations may explain the often reported observation thatafter the incentive plan has been stopped or the economy recovers, risky behaviour andaccidents return to their previous level. The bouncing back shows two important facets ofincentive plans. The positive aspect is that people were able - for a limited time - to reducetheir accident-related behaviour drastically, in some instances to zero, thus supporting RCT.However, underlying values and risk motivation were not significantly changed, as thelowered accident rate was triggered and stabilised through external rewards, thus not negatingRHT. The target level of risk is based on safety attitudes and the value of risk-taking which ismore likely to be changed through participative methods allowing people the freedom todesign, perform and control their own activities (Zink and Ritter, 1992).4.2. Using intrinsic motivation to change the target level of risk

Intrinsic safety motivation refers to the process that people will behave safely even in theabsence of external control and feedback agencies. If somebody works alone at home withnobody controlling, rewarding or punishing safe and unsafe behaviour, only those that haveintemalised safety values will anticipate dangers and adhere to safety standards as strongly aswhen working on a job under close supervision. This behaviour requires neither externalcontrol nor praise, but is self-designed, self-performed, self-controlled, and even self-rewardedor punished. Health and safety in public life (e.g. in traffic), on the job (e.g. work safety) andin private life (e.g. preserving health and eating properly) have very limited external controlsand reward mechanisms. The police net is not tight enough to catch and prosecute the majorityof violators (low perceived risk). Supervisors on the job cannot control every movement onthe shop floor and the ministry of health cannot prevent unhealthy habits such as alcohol and


9/12

RHT: past problems and future promises 127

drug abuse at home. Thus, the motivation to use safe behavioural alternatives has to stem fromwithin people (target level of risk).

Zink and Ritter (1992) and Trimpop (1994c) suggest using participative methods toincrease intrinsic motivation for work and occupational traffic safety. Trimpop (1994a) arguesthat self-determination, participation and responsibility will alter peoples target level of risk,as one associates a higher value with actions that have been self-designed than with those thatare forced upon a person externally. Safety circles offer individuals or groups the opportunityto design their own safe working procedures, to produce safely and to monitor the quality oftheir safety work and strengthen peoples commitment to adhere to that behaviour (Porter andSmith, 1970).

Participative approaches have proven successful in quality circles, industrial safety circles,and are being examined in occupational traffic safety (Zink and Ritter, 1992; Muller-Demaryand Przygodda, 1992; Homdasch, 1992, 1995; Trimpop et al., 1995). It is much more difficult,however, to apply participative concepts to public and private life, which is usually not asorganised and structured as work. Studies examining predictions made by RI-IT in theapplication of participative measures have not been reported at all, but would offer a closerview of whether the target level of risk can be changed lastingly. Also, field studies assessingwhether peoples assessment of risk can be changed and whether this leads to a change in theirdesire for risk have been neglected. One reason may be that the notion that all people desirerisks to a certain - individual - degree is not a concept readily accepted by many safetyresearchers.

5 ConclusionsTo summarise, it was argued that RI-IT is far from becoming obsolete but offers ample

opportunity for further scientific debate as well as for preventing accidents and otherhealth-related problems. While one key component of RHT, namely behavioural adaptation toperceived risks (RCT), has found strong empirical support both in the laboratory and in thefield, the notion of a full homeostatic process has received mixed support and leaves importanttheoretical questions unanswered. Risk homeostasis theory has to broaden its perspective byincorporating new ideas (e.g. risk-taking behaviour is attractive, emotional factors triggerbehaviour, multiple target levels of risk), and applications, such as changing risk perceptionand target levels of risk by participative means, such as safety circles, rather than byincentives alone.

ReferencesAdams, J.G.U.. 1985. Risk and Freedom. Transport Publishing Projects, Cardiff.Adams, J.G.U., 1988. Risk homeostasis and the purpose of safety regulation. Ergonomics, 31: 407-428.Aschenbretmer, K.M. and Biehl, B., 1994. Improved safety through improved technical measures? Empirical studiesregarding risk compensation processes in relation to anti-lock braking systems teds. R.M. Trimpop and G.J.S.

Wilde), Challenges to Accident Prevention: The Issue of Risk Compensation Behaviour. Styx Publications,Groningen.

Aschenbretmer, K.M., Biehl, B. and Wurm, G.W., 1988. Mehr Verkehrssicherheit durch besserc Technik? Feldunter-suchungen zur Risikokompensation am Beispiel des Antiblockiersystems CABS). AbschluDbericht an die Bunde-


10/12


11/12


12/12

130 R M Trimpop

Streff, F.M. and Geller, E.S., 1988. An experimental test of risk compensation: Between-subject versus within-subjectanalyses. Accident Analysis and Prevention, 20: 277-287.

Svenson, 0.. Fischhoff, B. and MacGregor, D., 1985, Perceived driving safety and seatbeh usage. Accident Analysisand Prevention, 17: 119-133.Taylor, D.H., 1964. Drivers galvanic skin response and the risk of accident. Ergonomics, 7: 253-262.Taylor, D.H., 1976. Accidents, risks, and the models of explanation. Human Factors, 18: 371-380.Ttikle, IJ. and Gelau, C., 1992. Maximization of subjective expected utility or risk control? Experimental tests of

risk homeostasis theory. Ergonomics, 35: 7-23.Trimpop, R.M., 1990. Risk taking behaviour: development and empirical examination of risk motivation theory.

Ph.D. Thesis, Queens University, Kingston, Ontario, Canada.Ttimpop, R.M., 1994a The Psychology of Risk Taking Behaviour. Elsevier, North-Holland, Amsterdam.Trimpop, R.M., 1994b. Risk compensation and the interaction of personality and situational variables (eds. R.M.

Trimpop and G.J.S. Wilde), Challenges to Accident Prevention: The issue of risk compensation behaviour. Styx,Groningen, the Netherlands, pp. 135- 146.

Trimpop, R.M., 1994c. Motivation zur Arbeitssicherheit, Der Sicherheitsingenieur, 5: 28-46.Trimpop, R.M., Adoiph, L. and Rabe, S. 1995. Evaluation betrieblicher Verkehrssicherheits ma&&men im Rahmen

eines partizipativen Gesundheitsmanagementansatzes. Paper presented at the 8th Workshop: Psychologie derAr-beitssicherheit. Laubach, Germany.

West, S.M., 1985. Sex Differences in a Laboratory Test of the Risk Homeostasis Theory. B.A. Thesis. QueensUniversity, Kingston, Ontario, Canada.

Wilde, G.J.S., 1976. Social interaction patterns in driver behaviour. An introductory review. Human Factors, 5:477-492.

Wilde, G.J.S., 1978. Theorie der Risikokompensation der Unfallverursachung und praktische Folgerungen tiir dieUnfallverhiitung. Hefte zur Unfallheilkunde. 130: 134-156.

Wilde, G.J.S., 1982a. Tire theory of risk homeostasis: implications for safety and health. Risk Analysis, 2: 209-225.Wilde, G.J.S., 1982b. Critical issues in risk homeostasis theory. Risk Analysis, 2: 249-258.Wilde, G.J.S., 1984. Gn the choice of denominator for the calculation of accident rates (ed. S. Yagar), Transport Risk

Assessment. Proceedings of a symposium on risk in transport. University of Waterloo Press, Waterloo, Ontario,Canada.Wilde, G.J.S., 1985a. The use of incentives for the promotion of accident free driving. Journal of Studies on Alcohol,10: 161-167.

Wilde, G.J.S., 1985b. Assumptions necessary and unnecessary to risk homeostasis. Ergonomics, 28: 1531- 1538.Wilde, G.J.S.. 1986. Beyond the concept of risk homeostasis: Suggestions for research and application towards the

prevention of accidents and lifestyle-related disease. Accident Analysis and Prevention, 18: 377-401.Wilde, G.J.S., 1988a. Risk homeostasis theory and traffic accidents: Propositions, deductions and discussion ofdissension in recent reactions. Ergonomics, 31: 441-468.

Wilde, G.J.S., 1988b. Risk-taking in psychomotor and cognitive tasks as a function of probability of loss, skill andother person related variables (eds. T. Rothengatter and R.A. de Bruin). Road User Behaviour: Theory AndResearch. Van Gorcum Assen, Maastricht.

Wilde, G.J.S., 1991. Economics and Accidents: A Commentary. Journal of Applied Behaviour Analysis, 24: 8 I-84.Wilde, G.S J., 1992. Accident Prevention through Incentives for Safety in Industry and Road Traffic: an Analysis ofInternational Experience. In: Proceedings of the XIII. Intemationales GtS-Sommer-Symposium. Gelsenkirchen,Germany.Wilde, G.J.S., 1994a. Risk homeostasis theory and its promise for improved safety. (eds. R.M. Trimpop and G.J.S.Wilde), Challenges to Accident Prevention: The Issue of Risk Compensation Behaviour. Groningen, TheNetherlands, pp. 9-24.Wilde, G.J.S. 1994b. New techniques for determining subjects risk-taking tendency in their task performance (eds. R.Trimpop and G.J.S. Wilde), Challenges to Accident Prevention: The Issue of Risk Compensation Behaviour. Styx,Groningen, Netherlands pp. 119- 134.

Wilde, G.J.S., 1994c. Target Risk. PDE Publications, Toronto, Canada.Wilde, G.J.S., Claxton-Oldfield, S.P. and Platenius, P.H., 1985. Risk homeostasis in an experimental context (eds. L.Evans and R.C. Schwing), Human Behaviour and Traffic Safety. Plenum, New York, pp. 119-142.Wilde, G.J.S., Trimpop, R.M. and Joly, R., 1989. The effects of various amounts of ethanol upon risk taking tendencyand confidence in task performance. In: Proceedings of the th International Conference on Alcohol, Drugs, andTraffic Safety.Zink, K.J. and Ritter, A., 1992. Mit Qualit;itszirkeln zu mehr Arbeitssicherheit. Universum Vedagsanstah, Wiesbaden.

Documents

Trimpop_RiskHomeostasisTheory