Event-related brain potentials as indicators of visual recognition and detection of criminals by their use

An event-related potential (ERP) was recorded, using photographs as stimuli, in 12 subjects for attended, 9 subjects for non-attended conditions and 14 subjects for a simulated criminal investigation. An ERP was detected only when a subject recognized a familiar image (target) mixed with other, unfamiliar images (non-target), regardless of whether he was asked to attend to or neglect the target image. ERPs in the subject who watched each picture but tried to ignore the relevant picture (non-attended) were more activated at the parietal region than at the central region, in contrast with ERPs in the subjects who paid attention to each picture without trying to ignore the relevant picture (attended). In the simulated criminal investigation, only a simulated thief, but not a simulated innocent subject elicited ERP only after the picture of a criminal site or thing was intermingled with pictures bearing no relationship to the crime. These findings indicate that the ERP using photographs as stimuli is useful as an objective indicator of crime-relevance.