Temporal integration deficit in visual information processing by chronic schizophrenics

The primary objective of the present study was to evaluate speed of visual information processing of chronic schizophrenics and normal subjects. Retarded information processing by schizophrenics has been attributed to a dysfunction at the earliest stage of processing. In the present study, by using a backward-masking paradigm and varying target duration we were able to evaluate whether schizophrenic and normals conform to an iconic or visual persistence theory of processing. Also, we evaluated whether schizophrenic and normal information processing is a function of the total time a stimulus is available for viewing prior to disruption (stimulus onset asynchrony, SOA), or whether it is the time following the stimulus offset prior to disruption by the mask (interstimulus interval, ISI). The former conforms more closely to a visual persistence and the latter to an iconic notion of processing. The results indicate that schizophrenics and normals conform to the processing of information as a function of the SOA as opposed to ISI. However, schizophrenic processing during the period of temporal integration (i.e., up to 130 msec) was significantly retarded when compared to normal controls. These findings suggest that for chronic schizophrenics, visual signals associated with target processing during the temporal integration period have either decayed at a slower rate or are more unstable than those of normals. Also discussed is the compatibility of these findings with a visual persistence as opposed to an iconic model of information processing.