Abstract
Functional imaging suggests the presence of divergent face processing streams. The fusiform face area may be preferentially involved in recognizing identity, and the superior temporal sulcus in perceiving social signals like facial expression. However, this distinction may not be complete: some identity-related processing might occur in the superior temporal sulcus, for example. This is of interest as most prosopagnosic patients have medial occipitotemporal lesions that spare the superior temporal sulcus. We tested the hypothesis that the recognition of faces by prosopagnosic patients would be aided by the use of faces with emotional expressions. We administered four tests to five prosopagnosic patients. One was the standard Warrington recognition memory test, in which smiling or neutral faces are used to test short-term memory for faces. The second test used a similar procedure but with 48 afraid, sad or happy faces. The third was a test that used angry or happy faces during the encoding phase, but neutral faces for the recognition phase, and the fourth test reversed the phases of the third. Prosopagnosics with fusiform face area lesions performed worse with the emotional variant of the Warrington procedure, compared to the standard test. They were also worse when encoding emotional faces for recognizing neutral faces, than when encoding neutral faces for recognizing emotional ones, primarily because of difficulty when encoding angry faces. We conclude that facial expression does not enhance face recognition in prosopagnosia, but may instead interfere with it, particularly during the encoding phase.
This research was funded by NIH grant MH069898, the Canada Research Chair program, and a Michael Smith Foundation for Health Research Senior Scholarship