Information-processing characteristics of explicit time estimation by patients with schizophrenia and normal controls

The information-processing characteristics of time estimation have not been well-documented. This research investigated explicit time estimation to test whether (1) it can occur "automatically" and (2) the cognitive function generally known as "working memory" predicts accuracy of time estimation. Data on two tasks requiring explicit time judgement (time interval estimation and production) are reported for a sample of 43 normal, healthy controls and 19 inpatients with chronic schizophrenia. Each task was given in a standard (passing time interval is unfilled) and dual-task format (interval is filled by oral reading). Multivariate analysis of variance suggested that for both patients' and the normal controls' time estimation accuracy was (1) highly sensitive to whether a passing interval was filled with a concurrent activity such as reading and (2) predictable on the basis of age, education, and working memory skills. Also, the effect of the dual-task manipulation did vary as a function of psychosis for the Time Interval Production task. The data suggest that procedures for explicit time judgements do not occur automatically and utilize controlled processes such as working memory.