THEME, a new method for analyzing the temporal structure of responding on a two-choice task, is described. This method reveals the time relationships (temporal patterns) between all response events, even those not occurring in direct sequence. It selects those temporal patterns that are significantly different (p < 0.0001) from the patterns found in a random Poisson distribution of the same events. The method was applied to data from Lyon et al. (1986) in which n = 17 outpatient schizophrenics were compared with n = 17 age-, sex-, and education-matched normal control subjects. Results revealed that responding of schizophrenic outpatients, in comparison to control subjects, had a larger number of significant temporal patterns, more different types of patterns, and more branching (connectivity) of patterns at a higher level. The latter indicates a higher degree of internal structure. These results are not predicted by standard (DSM-III-R) diagnostic procedures, but are in agreement with studies of two-choice behavior in schizophrenia based on the Lyon-Robbins (1975) theory of behavioral change, which has possible relationship to dopamine/acetylcholine imbalance in the brain. Diagnostic procedures in schizophrenia might benefit from tests oriented toward these findings, which are also consistent with Bleuler's original descriptions of schizophrenic symptomatology.