Predicting criminal incidents on the basis of non-verbal behaviour: The role of experience

Abstract

Do experienced police officers have a superior ability to detect impending criminal acts? In order to test this Hypothesis 10 Closed Circuit Television (CCTV) clips were collected from real criminal events that occurred in and around Nottingham City Centre in the UK. Ten control clips were filmed specifically or chosen from existing footage to match the criminal clips, but did not contain any criminal activity. All clips ended abruptly, immediately before a real criminal act unfolding, or a non-criminal act in the control clips, and either the screen turned black, masking the video scene, or remained frozen on the final frame of the edited clip. Thirty police officers and 30 control participants watched the clips. At the end of each clip, participants were asked to predict what would happen next. Signal detection analysis indicated marginal evidence that police show greater accuracy in predicting clips that cut to a black screen compared with the general public. A stronger effect was noted in the analysis of the criterion, with police officers much more likely to predict a crime regardless of whether there was one. These findings provide promising evidence of experiential differences between police officers and the general public when identifying criminal and antisocial behaviour in CCTV footage, though the greater criterion bias effect suggests that experience may oversensitise individuals to non-verbal cues.