Abstract
The investigation of individuals with prosopagnosia has often suggested that the visuoperceptual mechanisms required for facial identity processing are dissociable from the mechanisms important for facial expression processing. However, Calder and Young (2005) have recently challenged this view. They propose that previous neuropsychological cases of dissociations between the two abilities might in fact result from trend dissociations. They point out that because facial emotion tasks tend to be easier than identity tasks the dissociation may result from differential difficulty. To better address this issue, we extensively tested individuals with developmental prosopagnosia on tasks of facial emotion processing. Most of these prosopagnosics do not complain of problems recognizing emotions, and they perform normally in some traditional tests of emotion recognition. We attempted to build tasks that put similar demands on facial identity and facial emotion perception by applying similar designs to test both abilities and using the same number of options of responses. We found that, when this is the case, most prosopagnosics also show some difficulties in the facial emotion tasks. Nevertheless, some cases seem to show disproportionate impairments with facial identity. These results are relevant to the discussion whether a single perceptual system or two separate systems are needed for processing identity and expression from the face.
Studentship from Foundation for Science and Technology (Portugal) for LG ESRC grant to BD (RES/061/23/0040)