The effects of varying noise and information loads on visual information processing of schizophrenics

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Previous research on the span of apprehension has shown that schizophrenics perform less well than controls when noise letters are presented with target letters. These researchers have hypothesized that the schizophrenic deficit is due to a malfunction of the central processor rather than to a sensory store trace of the incoming stimulus. Accordingly, it has been argued that the span of apprehension task provides a convenient measure of the central processor deficit.

Most studies suggest that as signal-noise similarity increases, performance on visual processing tasks decreases. Although researchers have investigated the qualitative variations of noise, few have investigated the quantitative variation of noise. A study by the present author that used a span of apprehension task with chronic schizophrenics suggests that chronic schizophrenics and institutionalized tubercular controls manifested a greater deficit on tasks of (1) increasing information levels and (2) increasing noise levels as compared to community controls.

Another study that used college students established that a significant interaction between noise and information levels was present. When the interaction was analyzed, significant differences were found between noise-level groups in the broad range of channel capacity suggested by Miller, i.e., 4, 5, 6, 7, 8, 10 and 12 elements.

The Present study was designed to test whether such an interaction would be found wiih chronic and acute schizophrenics. Increasing noise levels may impair performance to a greater degree with schizophrenics than controls as the number of elements to be processed approaches channel.


This article was originally published in Journal of Clinical Psychology. The full-text article from the publisher can be found here.

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Journal of Clinical Psychology


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