IMPLICIT MEMORY FOR WORDS PRESENTED DURING ANESTHESIA

Tests for implicit memory seem to be rather insensitive to the amount of attention given to stimuli during study. In the experiment reported here, the effect of a complete absence of attention during presentation of stimulus material on implicit memory performance was studied. Surgical patients were auditorily presented with exemplars of word categories during general anaesthesia. At the earliest convenient time after surgery, they were requested to generate category exemplars. Although none of the patients expressed any conscious recollection of events during the surgical episode, experimental patients generated significantly more critical exemplars than a control group. Apparently, information presented during anaesthesia can influence post-operative performance in an implicit memory task. Repetition priming seems possible even in the absence of attentional processing at the time of encoding. It is argued that the nature of the unattended encoding process can best be described as the automatic activation and strengthening of pre-existing memory representations.