Reduced range of sensory sensitivity in chronic nonparanoid schizophrenics.

A forced-choice auditory signal-detection method was used to test the hypothesis that, compared to acute paranoid schizophrenics, chronic nonparanoid schizophrenics would show a restricted range of sensitivity to environmental cues. Ability to detect the presence of an auditory cue, while concurrently tracking a ! visual stimulus, was measured under two conditions, auditory monitoring being given primary or secondary importance. In this task, a narrowed range of sensitivity implies a greater deficit in ability to detect the auditory cue when the primary focus is placed elsewhere. As expected, this deficit was significantly greater in the chronics in both initial and replication experiments. Discussion centered on the function of restricted sensitivity in limiting the range of both relevant and distracting stimuli that are responded to by chronic nonparanoid schizophrenics.