Estimating the speed of vehicles: the influence of stereotypes

Abstract

Davies and Patel (2005, Legal and Criminological Psychology, 10, 45–62) demonstrated that stereotypes associated with particular types of car influenced judgements of culpability in a road accident report. This study explores whether stereotypes influence judgements of the speed of different vehicles. In Experiment 1, participants observed films of a BMW 3 Series and VW Polo being driven at 20, 40 and 60 mph. Accuracy of speed estimates was high and no effect of stereotyping was observed. This finding was replicated in Experiment 2 when the stereotype of a ‘typical’ BMW or Polo driver was instantiated prior to viewing the films and despite participants predicting that the speed of the BMW would be substantially higher than the Polo. In Experiment 3, speed estimates were made unexpectedly a day after viewing the films. In accordance with the stereotype, the BMW was now judged as being driven significantly faster than the Polo at the same actual speed. Consistent with findings from person perception, these results suggest that when unambiguous countervailing information is present, stereotypical influences are minimised or overwhelmed, but much stronger effects occur when access to critical information is impaired or ambiguous. The implications of these findings for witness estimates of vehicle speed are discussed.