In Risk, Adams tackles the conventional view of risks as being an external factor which everybody does their best to avoid, and introduces the idea of the "Risk Thermostat" which is an assemblage of cultural filters, rewards and costs which colours our perception of risk. The idea of rewards and costs, of personal propensity to take risks and of the (often inaccurately) perceived dangers associated with individual behaviours is not especially new, but Adams cleverly analyses the perceptual filters by which, for example, rewards influence propensity to take risk, and arrives at some startling conclusions about balancing behaviour.
Essentially, we tolerate and even enjoy an element of risk in our lives. If someone tries to reduce that risk, for example by forcing us to wear a seat belt, then we will compensate by balancing behaviour, say by driving faster, until our internalised measure of risk returns to the preferred level. The idea that risk is both sought out, and culturally constructed, is what makes this book so clever. By culturally constructed I mean that the Western perception of risky behaviour on the roads would be greatly different from that found on the Indian subcontinent, for example.
Note that, in the "Risk Thermostat", changes in behaviour act on the rewards and the "accidents", which only influence the perceptual controls (perceived danger and propensity to risk) through cultural filters. So if we do not see a particular "accident" as likely, we may be inclined to take balancing behaviour bringing more "reward" (e.g. more speed) than is actually justified by the real level of risk posed. The lessons this offers to those who want to improve road safety are profound, and in many cases revolutionary. This kind of model may well be familiar to those who have studied control theory in any detail. I do not know whether the shared space experiments, where all road markings and signage were removed as a traffic calming measure, were influenced by Adams, but it seems to me a good example of how you would apply this model - by interfering with the perceptual filters (white paint and road signs) we force the driver to make his own judgements.
Adams came to public notice when he published a paper which suggested that seat belt laws had failed to save lives wherever they had been tried. The Government did not believe this, so the commissioned the Isles report - which showed that Adams was right. This was against policy, so was buried, and the law was introduced anyway. It failed to save lives.
Risk compensation is now a mainstream idea and few even attempt to deny that it exists. Although it can't be proved by formal scientific method (that would essentially require the proof of a negative, which can't be done), experiments such as the Munich taxi driver experiment have repeatedly produced results which support the theory.
Risk is a must-read bok for anyone active in any field involving safety, especially, I would say, road safety campaigners. Risk was published by Routledge in 1995, ISBN 1857280687 and is available from Amazon (4.5 star rating).