ENCODING, REMEMBERING AND AWARENESS IN LORAZEPAM INDUCED AMNESIA

The effects of lorazepam (1,2 mg) and placebo on encoding, remembering and awareness were assessed in a study with 54 healthy volunteers. Al l subjects studied stimulus materials in a levels of processing (L-o-p ) task. Half the subjects were assessed on an explicit memory task of word recognition and the other half were given an implicit memory task of word-stem completion. Following the implicit task, awareness of re trieval was further investigated by questions and by subjects' recolle ctive experience in recognising the actual words they had completed fr om stems. L-o-p effects and marked lorazepam-induced impairments were found in the implicit task of word-stem completion although the intera ction between L-o-p and drug effects emerged only as a trend in the da ta. Lorazepam-induced impairments on stem-completion may then be expla ined at least in part as being due to contamination by explicit retrie val processes, but we cannot rule out the possible role of drug effect s on perceptual processes at encoding. results from responses to ''awa reness'' questions and from analysis of subsequent recollective experi ence indicated that subjects were not aware of using explicit retrieva l during the implicit task. Results also replicated previous findings showing that both lorazepam and L-o-p independently affect performance in an explicit memory task of word recognition. Thus drug-induced def icits at encoding persist regardless of the level at which information is initially processed.