A laboratory measure of synchronization was used to assess the differential ability of schizophrenics, affectives, and normal controls to take advantage of stimulus predictability. It was hypothesized that (I) schizophrenics will perform on this task in a way that distinguishes the from other groups, (2) clinically observed motor anomalies will be associated with deficient motor synchrony, and (3) deficient motor synchrony will be associated with more severe clinical ratings of thought disorder. Twenty-one schizophrenic, 8 affective, and 16 normal controls were studied. The results were consistent with the hypotheses; schizophrenic subjects had distinctive performance patterns, especially at 40 bpm, which was associated with both motor and thinking disturbance. The authors discuss additional analyses that suggest that deficient motor synchrony is associated with negative symptoms, certain ward behaviors, and not with demographic variables, and that among umedicated schizophrenic subjects, the performance patterns are worse.