T R A N S P O R T A N D C O M M U N I C A T I O N S DRIVER AGGRESSION: THE ROLE OF PERSONALITY, SOCIAL CHARACTERISTICS, RISK AND MOTIVATION by Elizabeth M. Grey Thomas J. Triggs Narelle L. Haworth Human Factors Group, Department of Psychology, Monash University March 1989 Report No. CR 81 F E D E R A L O F F I C E O F R O A D S A F E T Y ii DRIVER AGGRESSION… DEPARTMENT OF TRANSPORT AND COMMUNICATIONS FEDERAL OFFICE OF ROAD SAFETY DOCUMENT RETRIEVAL INFORMATION Report No. Date ISBN ISSN CR 81 March 1989 0 642 51243 4 OR=0158-3077 CR=0810-770X Title and sub-title: Driver Aggression: the Role of Personality, Social Characteristics, Risk and Motivation Author(s): Elizabeth M. Grey, Thomas J. Triggs and Narelle L. Haworth Performing Organisation: Human Factors Group Monash University Clayton Vic 3168 Sponsoring Organisation: Federal Office of Road Safety GPO Box 594 Canberra ACT 2601 Abstract: The report addresses the topic of aggression in driving, with a consideration of a number of subject areas: theories of aggression; the definition of aggressive behaviour in driving; measurements of aggression; extreme forms of driver aggression; less extreme forms of driver aggression. The report’s conclusions focus on society’s role in aggressive behaviour, strategies for coping with aggression, including driver education and screening, and directions for future research. Key Words: Disclaimer Aggression, aggressive 1. FORS Research Reports are disseminated in the interests of information exchange. driving, driver behaviour, 2. The views expressed are those of the author(s) and do not necessarily represent risk assessment, risk those of the Commonwealth Government. measurement 3. The Federal Office of Road Safety publishes three series of research report (a) reports generated as a result of research done within the FORS are published in the OR series; (b) reports of research conducted by other organisations on behalf of the FORS are published in the CR series; (c) reports based on analyses of FORS’ statistical data bases are published in the SR series. Reproduction of this page is authorised This Adobe .pdf version created by Monash University Accident Research Centre, PO Box 70A, Monash University, Victoria, 3800, Australia. Telephone: +61 3 9905 4371, Fax: +61 3 9905 4363 DRIVER AGGRESSION… iii iv DRIVER AGGRESSION… Contents GENERAL INTRODUCTION.................................................................................................1 CHAPTER 1 APPROACHES TO THE STUDY OF AGGRESSION.......................................3 THEORIES OF AGGRESSION......................................................................................................3 Biological approaches...............................................................................................................3 Drive theories: The frustration-aggression hypothesis.............................................................4 Social learning theories.............................................................................................................5 OVERVIEW OF THEORIES OF AGGRESSION..........................................................................5 DEFINING AGGRESSION.............................................................................................................6 CHAPTER 2 THE ISSUE OF AGGRESSION IN DRIVING....................................................9 WHAT IS AGGRESSIVE DRIVING?............................................................................................9 THE MOTIVES OF DRIVERS.....................................................................................................10 THE SUBJECTIVE RISK OF CRASH INVOLVEMENT...........................................................13 Risk assessment......................................................................................................................13 The concept of risk homeostasis.............................................................................................14 Absence of subjective risk......................................................................................................17 OTHER FACTORS INFLUENCING AGGRESSIVE BEHAVIOUR..........................................20 Stress 21 Alcohol...................................................................................................................................21 Other drugs.............................................................................................................................22 Brain pathology.......................................................................................................................23 Conclusion..............................................................................................................................23 CHAPTER 3 METHODS OF MEASUREMENT....................................................................25 THE NATURE AND USE OF PSYCHOLOGICAL TESTS........................................................25 PSYCHOMETRIC TESTS USED IN THE MEASUREMENT OF DRIVER AGGRESSION....26 Problems with the use of projective and objective techniques...............................................27 Projective techniques..............................................................................................................27 Objective techniques...............................................................................................................29 Interview techniques...............................................................................................................32 Concluding comment..............................................................................................................32 CHAPTER 4 EXTREME FORMS OF DRIVER AGGRESSION............................................33 SOCIETAL ATTITUDES TOWARD DRIVING OFFENCES.....................................................33 THE RELATIONSHIP BETWEEN CRIME AND TRAFFIC VIOLATIONS.............................33 MOTOR VEHICLE CRASHES AS SUICIDE..............................................................................35 CRIMES OF VIOLENCE ON THE ROAD..................................................................................38 CHAPTER 5 LESS EXTREME FORMS DRIVER AGGRESSION........................................41 THE CONCEPT OF ACCIDENT PRONENESS..........................................................................41 DIFFERENTIAL ACCIDENT INVOLVEMENT.........................................................................43 PERSONAL FACTORS RELATED TO CRASHES....................................................................43 Methodological issues.............................................................................................................43 Personal characteristics of crash involved drivers..................................................................45 DRIVER AGGRESSION… v Personality Factors.................................................................................................................45 Social characteristics of crash involved drivers.....................................................................51 HIGH RISK OF CRASH DRIVER GROUPS..............................................................................53 Characteristics of drivers who drink and drive......................................................................53 Characteristics of young drivers.............................................................................................56 Other groups at risk: The mentally ill....................................................................................58 PREDICTING AGGRESSIVE DRIVERS....................................................................................59 CHAPTER 6 CONCLUDING DISCUSSION........................................................................61 INVOLVEMENT OF CRASH REPEATERS..............................................................................62 FOUNDATIONS OF AGGRESSIVE DRIVING.........................................................................63 The role of society..................................................................................................................64 STRATEGIES FOR COPING WITH AGGRESSIVE DRIVING................................................65 Screening drivers....................................................................................................................65 Modifying driver behaviour...................................................................................................66 Enforcement...........................................................................................................................66 Driver education.....................................................................................................................67 DIRECTIONS FOR FUTURE RESEARCH................................................................................68 REFERENCES.....................................................................................................................70 Figure FIGURE 1 HYPOTHETICAL COGNITIVE-BEHAVIOURAL MODEL OF THE INFLUENCE OF SOCIAL SKILL DEFICITS, HEAVY ALCOHOL USE AND HOSTILE-AGGRESSIVE PERSONALITY ON HIGH-RISK DRIVING. FROM DONOVAN, MARLATT AND SALZBURG (1983)....................................................................................56 Tables TABLE 3.1 TYPES OF PROJECTIVE TESTS USED IN THE INVESTIGATION OF DRIVER AGGRESSION...........................28 TABLE 3.2 TYPES OF OBJECTIVE TECHNIQUES USED IN STUDIES OF DRIVER AGGRESSION.....................................29 TABLE 3.3. SCALES DEVELOPED FOR INDIVIDUAL STUDIES..................................................................................30 TABLE 3.4 LISTS STUDIES THAT HAVE UTILISED INTERVIEW TECHNIQUES............................................................32 TABLE 5.1 PERCENTAGE CONTACT OF CRASH INVOLVED AND CRASH FREE DRIVERS WITH SOCIAL AGENCIES. DRIVERS CHOSEN FROM THE GENERAL DRIVING POPULATION OF LONDON, ONTARIO. (N = 96, CRASH GROUP, N = 100, CRASH FREE GROUP). ADAPTED FROM TILLMAN AND HOBBS, 1949)......................52 vi DRIVER AGGRESSION… EXECUTIVE SUMMARY This report addressed the topic aggression in driving and related areas of research. A range of different subject areas are reviewed including theories of aggression, factors contributing to aggressive driving behaviour, the measurement of aggression, the characteristics of driver groups at high risk of crash involvement, strategies for combating aggression in driving and the identification of a number of research issues. Approaches to the study of aggression There are a number of different theoretical approaches to the study of aggression. However, none are considered to be complete explanations but reflect the orientation and requirements of the researchers who developed them. Biological theories consider aggressive behaviour to be innate, although specific responses can be modified by experience. In the psychoanalytic tradition, the frustration-aggression hypothesis proposes that the origin of aggressive behaviour is to be found in external factors. Finally, social learning approaches argue that aggression is a learned response through observation or imitation of socially relevant others. Aggression is the result of the norms, rewards, punishments and models to which individuals have been exposed. Although these three approaches differ in the emphasis they place on the role of biological (genetic inheritance and evolutionary) processes and experience (learning through exposure to environmental factors), they generally assume that aggressive behaviour is the combined result of these factors. Defining aggression in driving Aggression can be defined as any behaviour directed at causing physical or mental injury. However, as Bandura (1983) points out, the classification of an act as aggressive depends on subjective judgements of intention and causality. For the purposes of this report, the concept of intent is useful in discriminating between driving acts where the intent was to cause harm and other driving acts which reveal a willingness to chance dangerous outcomes in order to fulfil the driver's motives. This latter situation necessarily encompasses behaviour in which the driver may not intend to harm other road users and may not be aware that significant risk is involved. Two definitions of aggression in driving are proposed which encompass the range of possible aggressive behaviours. The first definition of aggression in driving includes what would normally be classified as extreme behaviour. These are acts of murder, suicide and wilful and malicious assaults (physical or psychological). The second definition encompasses the concept of risk taking. This driving behaviour is aggressive in appearance, but does not necessarily imply intent to cause harm, although it may subsequently put other road users at risk. The motives of drivers The behaviour of the road user (of which aggression is one aspect) needs to be considered within the framework of the social and psychological context in which it occurs. The view is expressed that the road user's behaviour is seen as reflecting a balance between personal motives (for example, thrills, the desire for speed or position in the traffic stream) and the subjective risk of crash involvement. Central to this view is the argument proposed by Naatanen and Summala (1974, 1976) that drivers in general do not perceive any risk of crash DRIVER AGGRESSION… vii involvement. This lack of subjective risk of accident involvement allows drivers to fulfil a variety of other needs. Another approach to the concept of subjective risk has different implications for driver risk taking. This is the concept of risk homeostasis which argues that road users always operate at the maximum level of risk that they are prepared to accept. This theory assumes that the driver is aware of and desires the level of risk he or she is taking. Other factors may also influence aggressive or risky behaviour. There is evidence that stress and alcohol may influence aggressive behaviour. In contrast, however, there appears to be relatively little information available with regard to the effects of other drugs and disease on aggressive behaviour. Methods of Measurement For the most part, investigations of aggression in driving have focussed on the evaluation of personality variables. A large number of studies have used psychometric tests in order to measure or predict aggressive driving behaviour. Psychometric tests used in the investigation of aggression in driving have included; projective techniques, objective techniques, and psychiatric or more general interviews. The use of these tests is not without serious problems with regard to their reliability and validity. Adequately standardized tests employed in the correct way may provide useful information about an individual's personal characteristics, although it may be only qualitative in nature. Methodological issues Studies comparing driver characteristics and crash record have produced equivocal results. While many studies claim to have distinguished between crash involved and crash free drivers on the basis of particular personality or social traits, the majority of these findings have not been validated. These differences in findings may be due to differing or inadequate methodology. Methodological problems found in these studies include; inadequate control for variation in exposure and hazard level, small sample sizes, use of inadequately standardised tests, and failure to validate findings with different populations. Extreme forms of driver aggression There are a number of different dimensions to be considered when discussing aggression on the road. These include how society views traffic offenders and the association between crash involvement and crime (including suicide and murder) in the community. The argument is made that society for the most part regards people who break the law as deviants. However, this attitude does not extend to people convicted of motor vehicle offences. A number of researchers consider that these people are still regarded by society as law abiding citizens whose behaviour is not only tolerated but excused. Researchers have considered the idea that serious traffic offenders may be more likely to have criminal records than non-offenders. This idea has been extrapolated to argue that in societies in which there are high rates of violent crime there will also be high rates of deaths and injuries by motor vehicle crash. The results of several studies suggest that there is a correlation between rates of death or injury by motor vehicle crash and violent crime. However, due to methodological problems, these results should be treated with great caution. viii DRIVER AGGRESSION… Fatalities which are the result of motor vehicle crashes are very rarely certified as suicides. Evidence suggests that probably substantially less than five percent of all deaths by motor vehicle crash are the result of suicide. In addition, while the characteristics of successful suicides and those involved in fatal accidents were considerably more deviant than the general population, greater deviancy was found in the suicide sample than in the crash sample. Other reports of wilful acts of violence or malicious damage on the road directed against other road users are rare although they do occur. Less extreme forms of driver aggression The concept of 'accident proneness' (as it is always referred to in the literature) has had a major influence on the study of personality factors of crash-involved drivers. Early investigations into personal factors and crashes originate at least in part from studies of accident proneness. Accident proneness can be defined (very broadly) as a propensity to have accidents. This propensity refers to one or more personality trait/s or type/s. The concept has a number of problems and has generally fallen into disfavour as it has failed to provide a means by which to predict individual accident involvement. While accident proneness has for the most part been put aside, the research into aggression in driving continues to embody the notion that some individuals by virtue of their personal characteristics are more likely to be involved in accidents than others. Drivers at high risk of crash involvement exhibit a broad range of personal and social characteristics. Certain demographic features are associated with increased risk of being involved in a crash. These include age less than 25, education of less than twelve years, being a semi-skilled or unskilled worker, single marital status and low socioeconomic status. Within this population of high risk drivers are a number of sub-groups which include crash-repeating drivers, people who drive under the influence of alcohol, young drivers (particularly young men) and possibly the mentally ill. Personal factors which have been identified as associated with motor vehicle crashes include generally high levels of aggression and hostility, competitiveness, less concern for others, poor driving attitudes, driving for emotional release, impulsiveness and risk taking. A background of social disruption and deviancy appears to be more common amongst high crash and/or violation drivers. The potential value of research into the personality and social characteristics of problem drivers lies in establishing effective means of predicting crash reliability. However, while some consistency has been found in these characteristics, there appears to be no single test or test battery by which individual accident liability can be predicted. The role of aggression in driving The attention focussed on the role of aggression in driving and the personality characteristics of repeated crash and conviction-involved drivers appears unwarranted given the likely contribution of these factors to crash causation. The accurate identification of such individuals is problematic. Furthermore, the effect of removing these individuals from the driving population would appear to be comparatively small as they can be considered to constitute only a small proportion of the driving population. Also, in general the composition of the crash repeater group is not constant from year to year. The extent of the problem also needs to be questioned. A study investigating the contribution of aggression to road crash statistics DRIVER AGGRESSION… ix claims that of the human factors identified as being involved in crashes only 0.6 percent were identified as frustration or aggression and 1.6 percent as reckless driving (Sabey and Staughton, 1975 cited in Hampson, 1984). Concluding comments There can be little doubt that there is a substantial learned component (at least in the ways and situations in which aggression is expressed) to aggressive behaviour. The argument is made that society as a whole determines the level of safety margins. Risk taking and competitiveness can be considered, in part, to be encouraged by society. Further understanding of the context in which aggressive driving takes place is required. Possible strategies for coping with aggressive driving include; screening drivers and modifying driver behaviour (enforcement and driver education). However, attempts to modify driver attitudes have been largely unsuccessful. Further research is required to identify the reasons for the general lack of effectiveness of driver education and publicity campaigns. The study of risk taking and risk assessment by drivers may be a more productive line of research than attempting to identify aggressive personality traits. Greater understanding of the contexts in which aggressive or risky driving takes place is required. The study of the personality and social characteristics of crash involved drivers may not be productive as these traits have been found to change with time, age and situation and cannot yet be used to predict accurately the crash history of individual drivers. Any further research investigating possible causal links between aggression and road traffic crashes using psychometric testing needs to employ stricter methodological controls than those used to date. Given the apparently small number of drivers involved repeatedly in crashes and the inadequacy of the psychometric instruments available, it may be more productive (in terms of countermeasures) to concentrate on other areas of research. x DRIVER AGGRESSION…