The need to relate cognitive deficits to specific behavioral referents of schizophrenia

The implicit rationale for many cognitive studies of schizophrenia hinges on the recognition that verbal communication generated by patients with this disorder is often elusive or difficult to comprehend. This observation has led to the inference that a cognitive dysfunction, which mediates the production of discourse failure, is characteristic of schizophrenia. Unfortunately, most investigators have chosen to examine this type of hypothesis by comparing heterogeneous groups of schizophrenic patients (without regard to whether they exhibit verbal communication impairment) with various control samples; they have not studied the association between cognitive processes and specific schizophrenic symptoms. Data are presented from two studies indicating that such relationships, even when highly plausible, cannot simply be presumed. In both studies, one with adults suffering from schizophrenia and the other with children at risk, a laboratory measure of referential communication failed to be strongly related to language disorder. These data suggest that future investigators should specify the features of schizophrenia that are expected to correlate with their laboratory measures and empirically evaluate these relations.