Implicit learning of new faces in prosopagnosia: an application of the mere-exposure paradigm.

A prosopagnosic patient was shown faces with which he had no prior experience, and was then given two-alternative forced choice recognition ("which of these faces did you see before?") and preference ("which of these faces do you like better?") tasks to assess learning. The patient showed normal preference for target faces, despite the fact that recognition of the faces was nil. This suggests that at least some prosopagnosics show implicit learning of new faces. The patient's normal preference for target faces is conceptualized as a "perceptual fluency" effect similar to that seen in more global forms of amnesia.