The role of head movement and pinnae in auditory localization in schizophrenia and psychosis.

This experiment examined the hypothesis that schizophrenics are less able than normals to make use of information concerning self movement when performing auditory localization tasks, and, therefore apply an alternative localization strategy, probably involving use of the pinnae. In this study three groups (healthy controls, schizophreniform patients and chronic schizophrenics) were compared in four experimental conditions: (1) head-movement and free pinnae; (2) static head and free pinnae; (3) head movement and covered pinnae; and (4) static head and covered pinnae. All subjects perform better with head movement than without it, with pinnae than with covered ones. Schizophreniform patients were affected more than normals by pinnae covering. This difference did not reach significance when normals were compared with chronic schizophrenics. A pronounced susceptibility to pinnae manipulation, correlated with medication level, appeared in the combined patient group in the moving condition. It was suggested that schizophreniform subjects, as compared to healthy controls are more depended on pinnae generated information for auditory localization and less able to compensate for its absence with movement generated information. The possibility that the effect is related to psychosis as such, rather than to schizophrenia in particular, was considered.