Face processing by deaf ASL signers: evidence for expertise in distinguished local features.

Several previous studies have shown that ASL signers are 'experts' on at least one test of face processing: the Benton Test of Face Recognition, a discrimination task that requires subjects to select a target face from a set of faces shown in profile and/or in shadow. The experiments reported here were designed to discover why ASL signers have superior skill as measured by this test and to investigate whether enhanced performance extends to other aspects of face processing. Experiment 1 indicated that the enhancement in face-processing skills does not extend to recognition of faces from memory. Experiment 2 revealed that deaf and hearing subjects do not differ in their gestalt face-processing ability; they perform similarly on a closure test of face perception. Finally, experiment 3 suggested that ASL signers do exhibit a superior ability to detect subtle differences in facial features. This superior performance may be linked both to experience discriminating ASL grammatical facial expression and to experience with lipreading. We conclude that only specific aspects of face processing are enhanced in deaf signers: those skills relevant to detecting local feature configurations that must be generalized over individual faces.