Harrison (1998) is making the general point that the development of programs to reduce road accident numbers by influencing driver behaviour requires a broad focus on a wide range of psychological theories, particularly theories of decision making. Obviously, he is right. No theory is ever "true". Theories that prove to be useful survive and develop, and theories that do not are used less and less frequently until they are forgotten. General deterrence theory has served us well in the road safety area, in that it explain the success - or lack of success - of a lot of programs very well, it enables new approaches to be developed and trialed, and programs developed as a result of this process have been shown to be effective. As currently formulated, it is applicable to a limited range of behaviour only. It predicts that the threat of punishment would have no effect on many kinds of behaviour; I am not aware of evidence showing effects in these areas. Other theories that are useful in the road safety area are used where appropriate. If theories that would take the place of deterrence theory gain support, then no doubt the use of deterrence theory will wane. The point of my original comment, however, was to put the view that the evidence that deterrence theory is useful has not had as much impact on psychologists as it should have, and to suggest that psychologists interested in developing behavioural change programs consider applying it. If Harrison is saying that there are other theoretical approaches purporting to explain the link between legislation, enforcement, and behaviour change that have at this time been shown to have more explanatory or predictive power than deterrence theory, I do not agree. (A)
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