An Ecological and Objective Neural Marker of Implicit Learning of Unfamiliar Identities

Fast Periodic Visual Stimulation (FPVS) combined with electroencephalography (EEG)is increasingly used to characterize neural mechanisms of visuo-perceptual processingof face identity processing. We developed a novel paradigm to measure implicit identitylearning through repetition using ecologically valid stimuli involving variationscharacteristic of forensic material. A demographically diverse cohort of neurotypicalcivilians and law enforcement professionals with normal face processing abilitiesserved as participants. We measured neural responses to a 1-Hz tagged oddballidentity embedded within a 6-Hz stream of base images, using high-quality mugshot,and CCTV-like stimuli. Extending previous findings, we report neural signatures ofimplicit identity learning through brief, repeated, passive exposure. Critically, however,this was only found for high-quality mugshot, but not CCTV-like images. We suggestthat our method could prove valuable in forensic settings where objective validation offace processing ability is crucial but not commonplace, e.g., assessment of lawenforcement experts and eyewitnesses.