Abstract
One of the few unquestionable facts in safety research is that drivers differ in the likelihood of their becoming involved in accidents. This paper sets out to give a brief description of a study carried out jointly by TRL (Transport Research Laboratory) and the University of Surrey to investigate the mechanisms that might lie behind this differential risk in accident liability. A four factor model of response to risk is discussed, covering hazard detection, threat appraisal, action selection, and implementation.