AbstractPreparatory interval, the length of time between a warning signal and the imperative stimulus, has been a major independent variable in studies that have examined reaction times of schizophrenics. Based on the hypothesis that schizophrenics have difficulty maintaining a heightened “set” to respond, long preparatory intervals (e.g., 7 seconds) have been predominant. However, long preparatory intervals do not permit an evaluation of the time course required to attain a heightened attentional state. This study employs preparatory intervals that range between 0 and 4000 msec in order to assess the arousal and maintenance of a heightened attentional state in schizophrenics (N= 10) and a normal control group (N= 10). The data suggest that schizophrenics may attain a heightened alertness more rapidly than normals. Schizophrenics are unable to maintain this state of alertness as competently as normal subjects. A hypothetical rationale for this finding is propo