Each hemisphere's ability to sustain attention over extended time periods was investigated in 14 schizophrenics and 17 controls using dichotic detection tasks. Schizophrenics produced significantly higher rates of omission errors, as compared to that of commission errors. The rates of omission errors for schizophrenics fluctuated markedly, while the rates of commission errors remained fairly constant. Primarily due to the fluctuation of omission errors, the detection index decreased progressively when schizophrenics were engaged in right-ear tasks. These results suggest that schizophrenics demonstrate a deficit concerning ‘response set’, especially in the left hemisphere. It is feasible that there may be a correlation with disturbances in integration mechanisms of both hemispheres in schizophrenics.