By Gerald J S Wilde. (Pp 234.) Toronto: PDE Publications, 1994. ISBN 0-9699-12404.

In Target Risk, Professor Gerald Wilde of Queen's University in Ontario, Canada assembles an impressive body of theory and evidence to support a provocative conclusion: the only effective strategy for achieving substantial and durable reductions in the rate of injury in a population is to increase people's desire to be safe and healthy. Traditional measures of injury prevention—engineering, education, and enforcement—are doomed to failure because they do not alter the “target levels of risk” that govern risk taking behaviors. The process of “risk homeostasis” will ultimately undermine all non-motivational countermeasures, since people will alter behaviors to achieve an equilibrium between the overall amount of risk they perceive and their overall desired level of risk. The key to success, Wilde argues, is “expectationism”: promoting people's interest in their future wellbeing in order to motivate adoption of smaller risk targets.

Wilde is not arguing that people enjoy or seek risk of injury. Like behavioral decision analysts and economists, he postulates that people select or accept risk targets in order to achieve other desired ends in life. When safer highways are built, drivers trade some or all of the extra safety for faster travel speeds and more relaxation (and inattention) in driving. When road conditions deteriorate (due to ice or fog), people sense elevation in risk and respond by slowing down and driving with more care. Using variations on this adaptation theme, Wilde challenges the effectiveness of most mainstream injury prevention measures: seat belt laws, antilock brakes, traffic lights, driver training/education, crackdowns on drinking and driving, highway design improvements, motorcycle helmet laws, you name it! Even more provocatively, Wilde hints that any long term progress that might be made in fatal injury could be offset by increases in the risk of fatal diseases (since people's overall risk target is maintained).

Technical specialists will certainly find fault with Professor Wilde's handling of a variety of complex empirical questions. For example, I thought his discussion of the association between the business cycle and injury frequencies was fair and insightful, yet his assessment of the effectiveness of safety belt use laws was highly selective, one sided, and arguably deceptive. Professor Wilde also has a tendency to see risk homeostatic explanations behind all empirical anomalies. Again, on safety belt use laws, Wilde notes that if belts are 50% effective in saving lives, and if belt use rates increased 50 percentage points following laws, why didn't laws cause an immediate 25% decline in occupant fatality counts? (Wilde is correct that few jurisdictions have experienced 25% reductions in fatalities after belt laws.) Aha, Wilde asserts, maybe drivers offset the benefit of the safety belts by taking more risks. Some alternative explanations that Wilde ignores are (a) the most crash prone drivers (for example, drunks and young males) may be least likely to comply with the law, (b) the 50% increase in use is an exaggeration, and even (c) the 50% effectiveness number may be biased upward (we once thought belts might be 60–90% effective).

Yet I would urge specialists to overlook Wilde's handling of detailed technical matters because such focus can cause the reader to shortchange Wilde's overall message. It is a message that the field of injury prevention needs to hear. We spend remarkably little effort on bottom-up approaches to motivating safety (for example, incentives) and inordinate resources on top-down measures aimed at protecting people from their folly (for example, helmet laws and speeding controls). A deeper understanding of the motivational barriers that frustrate injury prevention measures is critical to the advancement of our field. Professor Wilde makes a lasting contribution by shedding some light on this neglected area.

This book has a length of 234 pages. It is comprehensive in topic coverage. The topics are as follows: the concept of homeostasis, compact theory of risk taking, theory of risk homeostasis, deductions and data, intervention by education, remedy by engineering, enforcement action, risk homeostasis in the laboratory, individual differences, and motivating for safety and health.