Schizophrenic patterns of dichotic shadowing performance.

This study sought to utilize dichotic shadowing tasks in the investigation of differences between schizophrenics and controls and, secondarily, between paranoid and nonparanoid schizophrenics. Sixteen subjects from each of four diagnostic groups--paranoid schizophrenics, nonparanoid schizophrenics, psychiatric controls, and normal controls--were tested in dichotic shadowing under one of two instructional conditions ("ignore the left ear" or "listen to both ears"). Schizophrenics made more errors with distraction, showed poorer ?recall of target material than did controls, and were abnormally insensitive to task instructions. This was interpreted as supporting previous reports that schizophrenics are lacking in selective attentional ability, deficient in retrieval of information, and inefficient in the sense of being unable to adapt to task instructions. In addition, recall and recognition results indicated that distraction affected paranoid and nonparanoid schizophrenics somewhat differently, resulting in overinclusion for paranoids but general response disruption or overexclusion for nonparanoids.