Figure 9.14: Implicit memory without explicit memory As shown in the graph, H. M., the patient with temporal-lobe amnesia, improved from session to session in a mirror-tracing task, even though at each session he could not remember having performed the task before. The task was to trace a star under conditions in which the star and hand could be seen only in a mirror so that movements had to be made oppositely from the way in which they appeared. An error was counted whenever the stylus moved off the star’s outline. The data points on the graph represent the average number of errors per trial for the seven trials that occurred in each session. Sessions occurred on three successive days and then after delays of 1 week, 15 days, and nearly a year.
(Based on data from Gabrieli et al., 1993.)