Rapid forgetting of faces in congenital prosopagnosia.

Congenital prosopagnosia (CP) is a life-long impairment in face recognition that occurs in the absence of any known brain damage. It is still unclear whether this disorder is related to a visual deficit, or to an impairment in encoding, maintaining or retrieving a face from memory. We tested CPs and matched neurotypical controls using a delayed estimation task in which a target face was shown either upright or inverted. Participants were asked to select the target face out of a cyclic space of morphed faces that could either resemble the target face, or not. The inclusion of upright and inverted faces enabled to examine the extent of the face inversion effect, a well-known face specific effect often associated with holistic processing. To enable disentangling visual from mnemonic processing, reports were required either following 1 and 6 sec retention interval, or simultaneously while the target face was still visible. Controls showed slower forgetting of upright compared to inverted faces. In contrast, CPs exhibited rapid forgetting of upright faces that was comparable to their performance and to performance of controls on inverted faces. Such forgetting was evident in random errors in which the selected faces did not resemble the face in memory, implying a time related decrease in the probability to access the correct face in memory. Importantly, CPs exhibited no inversion effect across all retention intervals, including the simultaneous one, suggesting that their abnormal rapid forgetting could be explained by an impairment in holistic visual processing of upright faces.