Excerpts from Target Risk

 

Date: Tuesday, 30. June 2009

By Gerald J.S. Wilde
PDE Publications, 1994
Dr. Gerald J.S. Wilde is a leading authority on risk behavior, and the originator of the theory of "risk homeostasis." This theory proposes that individuals have a target level of risk that they accept in their everyday lives and that interventions designed to improve safety (laws, engineering, etc.) will fail unless this target level of risk is changed.

Why this book? Implications for public policy

"This book has been written in an effort to explain why traditional interventions are not effective and why some innovative ones are. Wider realization that the traditional ways do not work may stimulate willingness to innovate. Wider awareness of the effectiveness of alternative approaches to health and safety may increase willingness to debate the merits of limited or even society-wide implementation of expectationist measures against lifestyle-dependent death and disease, as well as against violence and abuse of the environment."

An important reading decision

"Human beings can never be totally sure of the outcome of their decisions. Ergo, all decisions are risky decisions. You have already taken a risky decision by opening this book and reading the first few lines, and having done so, you are now facing another: to read on or to put it back on the shelf.

And what do I do as the author of this book? It goes without saying that I would like you to read all of it, just as I wrote all of it. If you choose to read on, there is a chance, however slight, that you may afterwards feel that you could have put your time to better use.

If, right now, you put it back on the shelf, you may later be nagged by the feeling that you missed out on an opportunity to learn something of importance to your own life expectancy, to that of your loved ones or to people in general. So, which of the two risky decisions do you take?"

Risk Homeostasis Theory

"Risk Homeostasis Theory maintains that, in any activity, people accept a certain level of subjectively estimated risk to their health, safety, and other things they value, in exchange for the benefits they hope to receive from that activity (transportation, work, eating, drinking, drug use, recreation, romance, sports or whatever)."

How we spend our dollars...

"Specifically, it is argued that the traditional reliance on enforcement of laws, on informing the public of certain dangers, and on engineering the physical features of the human-made environment is not very productive towards greater health and safety insofar as these are dependent on human conduct. An effort is made to explain why this is so."

The famous Munich taxicab study

"Part of a taxi fleet in Munich was equipped with an anti-lock brake system-also known as ABS. This type of brake system prevents the wheels from locking up under extreme braking conditions. It offers the advantage of improved steering control over the vehicle during rapid deceleration, especially on slippery road surfaces. The system makes it possible to change the direction of the car and abruptly reduce speed at the same time, at a considerably reduced risk of losing control.

ABS brakes offer a perfect example of what was called a change in intrinsic risk towards the end of Section 3.4-a change in the objective accident loss expected if drivers don't change their behaviour when a 'safer vehicle' is made available. However, according to risk homeostasis theory, drivers are expected to change their behaviour and to maintain their accident likelihood per hour of driving as long as the target level of risk is not altered."

..."The drivers were not aware that their driver behaviour was being observed and the observers did not know whether they were in a taxi with ABS or without. The drivers did, of course, know whether or not they were operating an ABS cab, because of their familiarity with the car they were driving.

Subsequent analysis of the rating scales showed that drivers of cabs with ABS made sharper turns in curves, were less accurate in their lane-holding behaviour, proceeded at a shorter forward sight distance, made more poorly adjusted merging maneuvers and created more 'traffic conflicts'."

..."The Munich taxicab experiment attracted a great deal of attention, not only in the professional circles, but also in the popular press. Newspapers carried articles about it and Bavarian Television wanted to show the viewers what had happened. As the experiment had already been completed, they decided to re-enact the experimental manipulation and the way the drivers had responded."...

On traffic lights and accidents at intersections

"Traffic lights are not to be condemned, but-contrary to naive opinion among some professionals and the general public-they serve no safety purpose, not even in the intersections proper or in their immediate vicinity. Numerous studies on the effect of traffic lights on accidents have compared the numbers of accidents at intersections before and after installation.

The effect is that fewer right-angle accidents happen, but more rear-end accidents, as well as left-turn and side-swipe collisions, occur, and the total frequency remains roughly the same. The latter is also true for the average severity of intersection accidents. Although driver actions are drastically altered by these devices, accident loss is not, and the risk remains the same."

Differences between individuals...

"Even if there were such a thing as a general risk-taking trait, there is a further reason for the weakness of association between a personality trait such as this, or any other personality trait, and accidents. This is because the tendency to have accidents is not a stable human characteristic."

Differences between situations...

"It is evident that risk taking is not a personality trait that is consistent from one situation to another. Similarly, the tendency to have accidents is not consistent from one time period to another. To believe otherwise may well be an example of the 'fundamental attribution error'. This expression is used by social psychologists to refer to the fact that people typically attribute another person's behaviour to that person's lasting character and not often enough to that person's passing state or the prevailing environmental condition."

Do "accidents" just happen or can we control them?...

"Some studies may actually lead to overestimation of the relationship between personality and what little stability there is in accident involvement. This can happen when current scores on personality tests are investigated on their association with past accident record. Take the case of 'external locus of control'. This term refers to persons who attribute the occurrence of important events, such as accidents, to external factors, rather than to their own doing.

The latter is called internal locus of control. When applied to driving, external locus of control is measured in terms of the respondents' agreement with statements like: 'driving with no accidents is merely a matter of luck' and 'most accidents happen because of bad roads, lack of appropriate signs, and so on'. Internals typically endorse statements such as 'accidents happen because drivers have not learned to drive carefully enough'."

Managing risk...

"...If a person's decision-making or vehicle-handling skills are poor, that person's level of perceived risk should be high, and if it is not, this reflects overconfidence in one's skills. The same holds for sensory abilities. To be colour-blind or hard of hearing does not imply a significant increase in accident liability, provided the driver considers these handicaps in the estimation of risk.

Poor night vision will not increase a person's accident risk unless the person is unaware of it or is willing to accept high levels of accident risk. Deficiencies in skills and sensory functioning, other things being equal, can increase a person's accident likelihood only to the extent that these deficiencies are being underestimated by the person in question, and thus lead to an inappropriately low level of perceived risk."

Does cautious mean safe?...

"...Mrs. Cautious Driver presents an interesting paradox. She was very careful indeed, in fact, so careful that her behaviour was rather unpredictable to other drivers. This made her liable to having accidents. On the other hand, if everybody were to behave as cautiously as she, there would be fewer crashes."

An unpredictable result of enforcement...

"...In what is known as the 'Chicago Crackdown' on drunk driving, judges in that city agreed to impose a seven-day jail sentence on all persons deemed guilty of the offence, but in a period of six months, only 6% of over 6,000 drivers arrested for driving under the influence had actually received such a sentence. In New York State it was found that about 27% of all individuals arrested for violations including driving under the influence were never prosecuted.

It would seem that a law cannot be enforced if its strictness exceeds popular opinion about the immorality or deviancy of the act concerned. The approach that takes the form of punishing people for specific unsafe acts suffers from several other problems as well, some of which have been identified in the context of organizational psychology."

Incentives can be effective but...

"...It should be noted, however, that the attitude-shaping effect of modest awards can only take place after the operators have changed their behaviour for some minor external inducement. So, the award should be big enough to achieve some behaviour change to begin with. In some cases, a small material reward might imply a major social reward because of its symbolic function. Safe behaviour may thus become 'the right thing to do'. This might help explain why a modest incentive such as free licence renewal for one year produced a major reduction in the accident rate of California drivers."

Speed limits...

"...We will return to this issue in the next chapter, but it's worth noting that enforcement of speed limits may merely have the effect of 'accident migration'. A German study reports a 21% reduction on an expressway following the introduction of a speed limit where no limit had existed. A stretch of expressway running parallel to the one with the new speed limit experienced a 29% increase in accidents, apparently as the result of the fact that drivers who did not want to forgo speedy progress simply took an alternative route."

Another perspective on policy...

"...Suppose we are dealing with a government that is fully aware of the tremendous costs of traffic accidents to its jurisdiction. Suppose, too, that we are dealing with a government that wishes to play a leadership role in reducing the traffic accident rate per head of population, rather than to remain a mere follower of existing public attitude and conduct.

In that case, the answer to what a government could do in order to reduce the traffic accident rate is very simple: (a) assume public responsibility for automobile insurance, and (b) impose insurance fees that take account of each individual driver's past accident record and of the requirements for effective incentive programming described above.

In doing so, a government would be able to achieve two things: it would pull itself up by its own bootstraps in becoming more concerned about safety promotion than before, and it would enhance the general public's desire for safety and strengthen public support for government action toward that goal."

"Expectationism"-a new kind of strategy...

"In connection with incentives for safe performance, it is of interest to note that they may be viewed as just one example of a wider class of interventions that hold the promise of reducing much more than the fatal accident rate per capita. They also hold promise for reducing lifestyle-dependent disease and death rates, as well as diminishing the level of violence in society."

"... Expectationism is the name of the preventative strategy for reducing the accident rate and lifestyle-dependent disease and death rate per head of population by enhancing people's perceived value of the future. It comes in two varieties, and these may be called 'specific' and 'general'."

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verkehrssoziologe,

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