Stimulus overinclusion (difficulty in attending selectively to relevant stimuli) has been hypothesized as an important underlying factor in schizophrenia. The present research represents an empirical study of this formulation. A test for stimulus overinclusion was administered to 80 acute schizophrenics and 119 acute nonschizophrenic patients during the first week of hospitalization, and to 53 "normal" controls. The patients were retested six weeks later, after their acute symptomatology had diminished. The results suggest that (1) schizophrenics score significantly higher on stimulus overinclusion, but it is unlikely that stimulus overinclusion is an important etiological factor for all or most early schizophrenics; (2) periods of acute upset lead to some increase in stimulus overinclusion; (3) stimulus overinclusion is found in "normals" as well as patients; and (4) consistent relationships between stimulus overinclusion and personality variables found for patients are similar to those relationships found for normals.
Harrow M, Tucker GJ, Shield P. Stimulus Overinclusion in Schizophrenic Disorders. Arch Gen Psychiatry. 1972;27(1):40-45. doi:10.1001/archpsyc.1972.01750250032003