ABSTRACT
Tilley's interest in evaluation, and his subsequent engagement by the then Police Research Group of the Home Office (PRG) to undertake assessments of individual preventive schemes implemented within Safer Cities (SC), seemed initially a little threatening. The offender perspective was, and is, deliberately neglected by situational prevention theorists but the SC schemes covered both situational and offender-oriented action. Mechanisms operate at different levels. The two over-arching mechanisms by which situational crime prevention works are an increase in costs or a decrease in benefits. At a slightly lower level of abstraction are the five mechanisms groups known as increasing risk, increasing effort, decreasing reward, reducing provocations and, removing excuses. Mechanisms are now starting to permeate crime science from other domains. Significant among these is the cognitive/neuroscience of decision-making. A challenge for crime scientists is how to articulate the diverse mechanisms underlying everything from human perception, reaction, decision, behaviour and learning.
