Normal gaze discrimination and adaptation in seven prosopagnosics.

Sensitive gaze perception is critical for social interactions. Neuroimaging and neurophysiological results and the unique demands of gaze processing have led to suggestions that gaze is processed by different mechanisms than other aspects of faces. Neuropsychological data however provides little support for this possibility. We administered gaze discrimination tasks to six developmental prosopagnosics and one acquired prosopagnosic who exhibit identity perception deficits. First we examined whether the prosopagnosic participants could discriminate between straight and averted gaze normally. The performance of the control and prosopagnosic groups was very similar, and all of the prosopagnosics scored in the normal range. To assess whether the prosopagnosics represented gaze information like the controls, participants were tested on the discrimination task following adaptation to leftward and rightward gaze. The control and prosopagnosic groups both showed strong adaptation in the expected direction, and each prosopagnosic showed normal post-adaptation performance. These results indicate that gaze discrimination and representation is normal in these prosopagnosics. Their dissociation between impaired identity perception and normal gaze perception provides support for models of face processing suggesting that these aspects of face processing involve separate mechanisms.