Improving eyewitness recall for licence plates

Two methods for maximizing the completeness and accuracy of eyewitness recall for licence plates were evaluated in this research: (1) asking questions derived from generally accepted principles of memory retrieval enhancement (Geiselman, Fisher, Firstenberg, Hutton, Sullivan, Avetissian and Prosk, 1984; Geiselman, Fisher, MacKinnon and Holland, 1985, 1986) and (2) providing subjects with a licence plate simulation device to view and interchange alphanumeric characters. Undergraduate subjects viewed a series of slides portraying a young man, placing a television set in a car and driving down the street. With a seven‐character California plate in Experiment 1 (n = 151), subjects in the condition with the simulation device and cognitive interviewing had a significant 22 per cent increase in correct licence plate recall. The results were replicated in Experiment 2 (n = 108) with an 18 per cent increase in correct information using a six‐character plate. Errors appeared to be those letters adjacent in the alphabet to the licence plate letters.