Examining the Motion Advantage in Developmental Prosopagnosia

Research has shown that individuals with typical face recognition abilities are more accurate when recognising familiar faces from dynamic images compared to static. One explanation for this motion advantage, the social signals hypothesis, proposes that social cues carried in movement benefit face recognition by attracting attention to identity-specific facial features such as the eyes, nose and mouth. The current study sought to a) examine whether individuals with developmental prosopagnosia (DP), who show severe deficits in face recognition, benefit from motion during familiar face recognition and unfamiliar face learning; and b) examine the validity of the social signals hypothesis as an explanation for any observed motion advantage. Fourteen prosopagnosics and 16 controls completed a famous faces recognition task and an unfamiliar face learning task while their eye movements were tracked. On both tasks, DP and control participants demonstrated higher accuracy for faces presented in motion. Both groups directed a higher proportion of visual fixations to the internal features (eyes, nose and mouth) when faces were presented in motion relative to a static presentation. Conversely, the proportion of fixations directed to the external features (cheeks, chin and hair) was higher during the presentation of static faces. Irrespective of presentation style (moving or static), individuals with DP directed less attention to the internal features than participants in the control group. These results support the social signals hypothesis as a theory of the motion advantage in DP by demonstrating that social cues present in facial motion attract attention to identity-specific features, facilitating identity processing.