Memory disorder and subjective time estimation.
Time disorientation is a common feature of anterograde memory disorder caused by brain illness. This observation suggests that the subjective time constructions used to organize events are strongly dependent upon memory storage processes. This study evaluated one prominent cognitive theory of time estimation from the point of view of organic memory disorder. A severely amnesic subject and 10 unimpaired subjects were asked to estimate time intervals using methods gleaned from the cognitive study of subjective time estimation. Results strongly suggest that the ability to remember new information is required in order to maintain an accurate time perspective. The time context for this subject essentially resided in the past, roughly corresponding to the time of her original brain surgery for a dermoid cyst near the third ventricle. Her ability to estimate time intervals and general time perspective was constrained by her impoverished store of knowledge for personal experiences.