A total of 120 male hospitalized psychiatric patients (30 acute and 30 chronic schizophrenics, 30 acute and 30 chronic nonschizophrenics) were tested for reaction time (RT) with a random sequence of preparatory intervals (PI')s of 1, 2, and 8 seconds. Contrary to general expectation, anticipation rather than RT was the most important indicator of schizophrenia. As predicted, RT varied as a function of PI's; however, no differences were shown in the acute-chronic and schizophrenic-nonschizophrenic dimensions. Schizophrenic patients had more anticipatory responses than nonschizophrenic patients with the 8-second PI and when the prior PI (PPI) was shorter than the PI. RT was also found to differ as a function of the PPI of each trial. Fastest responses occurred when PPI=PI, next fastest when PPI< PI, and slowest when PPI>PI. When confounding effects of the PI were removed from the PPI analyses, group differences in response to the PPI disappeared. Results were discussed in terms of the attentional set formulations of Zahn and Shakow.