Matching identities of familiar and unfamiliar faces caught on CCTV images.

People can be inaccurate at matching unfamiliar faces shown in high-quality video images, even when viewpoint and facial expressions are closely matched. However, identification of highly familiar faces appears good, even when video quality is poor. Experiment 1 reported a direct comparison between familiar and unfamiliar faces. Participants who were personally familiar with target items appearing on video were highly accurate at a verification task. Unfamiliar participants doing the same task performed very inaccurately. Familiarity affected discriminability, but not bias. Experiments 2 and 3 showed that brief periods of familiarization have little beneficial effect unless "deep" or "social" processing is encouraged. The results show that video evidence can be used effectively as a probe to identity when the faces shown are highly familiar to observers, but caution should be used where images of unfamiliar people are being compared.