1. Objective
Developmental prosopagnosia (DP) is a life-long deficit in face recognition. The deficit is thought to be selective for faces, a hypothesis we tested by investigating patterns of associated and dissociated visuoperceptual and -attentional functions in a group of DPs.
2. Participants and Methods.
10 DPs and 20 matched controls participated in experimental tasks measuring recognition of faces, objects, letters, words, and scenes, as well as text reading, global-local processing (Navon’s paradigm), and visual attention / short-term memory. Performance was compared using both group and single case statistics.
3. Results.
We find an intriguing pattern of preserved and impaired functions in DP: Letter and word recognition, text reading, and visual attention / short-term memory were normal. For geographical scenes, simultaneous matching was normal, while there was a group difference in delayed recognition. Three DPs, however, showed a classical dissociation between impaired face memory and preserved memory for scenes. For object recognition, DPs are impaired, and show a correlation between the severity of the face recognition deficit and performance with degraded objects. In the Navon paradigm, we find that the global precedence effect (thought to reflect configural processing) is reduced in DP. This reduced global precedence effect correlates both with the DPs’ face recognition abilities, as well as their ability to recognize degraded (non-face) objects.
4. Conclusions.
The DPs show an informative pattern of preserved and impaired functions across tasks: In tasks relying on processing of global shape characteristics, they are impaired, while their performance is normal in tasks where parallel processing of individual characters or features are sufficient. We suggest that this pattern of performance can be explained by an abnormal delay in the derivation of global shape information, and that this general deficit may contribute significantly to the face recognition difficulties observed in developmental prosopagnosia.