In the absence of auditory information, deaf individuals must rely on visual input from facial expressions for emotional, social, and linguistic cues. In order to test the hypothesis that specialized experience with faces can alter basic mechanisms of face perception, 12 hearing adults and 12 deaf, native users of American Sign Language completed a battery of face perception tasks involving the perception of emotion and identity in expressive faces.

Studies 1 and 2 examined adults’ bias to fixate and attend to the top halves of faces. Both groups recognized individuals more accurately from isolated top than bottom halves of faces (Study 1) and from top halves of composite faces (Study 2). Emotional expressions were better recognized from the bottom halves in both studies. While hearing adults fixated the top halves of faces most often regardless of task demands, deaf adults often split fixations evenly between the top and bottom halves. Studies 3 and 4 examined the dominance of the right hemisphere in face perception, and the associated left visual field bias. Hearing adults judged emotion more accurately for faces presented in the left than the right visual field (Study 3), and for left as opposed to right sides of faces (Study 4). Deaf subjects showed no left side advantage in either study. Event-related potentials recorded in Study 4 demonstrated that although both groups showed right hemisphere asymmetries, hearing adults showed larger responses to left than right sides of faces, while the deaf group did not.

Therefore, compared to hearing adults, deaf adults showed a more diffuse pattern of gaze and attention across the face. This conclusion is supported by research on general attention patterns in the deaf and indicates that deafness may affect aspects of face processing that are not directly involved in signed communication. These studies suggest that face perception mechanisms can be altered by specialized experience and acquired skills, a finding that has important implications for further research not only on the deaf, but also on populations with social developmental disorders.