The ability of amnesic subjects to estimate time intervals.

Amnesic subjects suffering from Korsakoff's syndrome and post-viral encephalitis were assessed on their ability to estimate short temporal durations using two quite different tasks. In the first experiment subjects were required to reproduce and estimate intervals of between 3 and 96 sec. In the second experiment subjects carried out an automated Fixed Interval task using intervals of 15 and 30 sec. On both tasks the Korsakoff group were impaired at all intervals compared to an alcoholic control group, whereas the post-encephalitic subjects were unimpaired compared to a normal control group. The results suggest that temporal estimation can be independent of memory function. There was, however, evidence of a relationship between the ability to estimate time intervals and performance on a particular test of frontal lobe function, cognitive estimation. The results are discussed in relation to these findings and to theories of temporal perception.