Altered attention constitutes one of the most prominent clinical symptoms of schizophrenia. However, theories of attention deficit rest on relatively weak and indirect support. Knowledge of the functional and structural basis of attention dysfunction is therefore limited. This proposal outlines a means of providing new knowledge of attention deficit in schizophrenia by providing a more direct and rigorous test of the hypothesis of broadening and narrowing of attention in acute and chronic schizophrenia. Selective attention will be measured in information processing tasks that assess comparative differences in the functional visual field. The analysis will result in evidence that distinguishes the relative contributions of selective coding operations and orienting mechanisms (eye and head movements) to attention dysfunction. The proposed experiments will proceed beyond a demonstration of the fact of attention dysfunction to an examination of specific factors that contribute to an understanding of attention deficit. Preliminary data from two NIMH-funded studies indicate that there are significant and differential alterations in the functional visual fields of acute and chronic schizophrenics. Attempts will be made to replicate these findings, to test competing hypotheses, and to provide converging evidence for hypothesized differences in selective coding operations.