Specific Effects of an Amnesic Drug: Effect of Lorazepam on Study Time Allocation and on Judgment of Learning

Abstract

We investigated the effects of lorazepam, a benzodiazepine, on the allocation of study time, memory, and judgment of learning, in a cognitive task where the repetition of word presentation was manipulated. The aim was to assess whether lorazepam would affect the learning processes and/or whether the participants would be aware of the amnesic difficulty. A total of 30 healthy volunteers participated in the study, 15 of whom received a capsule containing the lorazepam drug (0.038 mg/kg) and 15 a placebo capsule. First, the accuracy of delayed judgments of learning (JOL) was measured in both groups. For the JOL ratings, results showed that all the participants benefited from word repetition. Although the overall performance was lower in the lorazepam than in the placebo group, the accuracy of the JOL ratings was preserved by the drug. Second, all the participants benefited from the repetition of learning, although the performances of the lorazepam-treated subjects remained lower than those of the placebo participants. The repetition of learning had an effect on JOL in both groups. Finally, the time spent learning each (allocation study time) pair of words was measured. For the placebo group, results revealed that study time decreased significantly with the frequency of presentation. For the lorazepam group, no effect of presentation frequency was found. Overall, our findings suggest that the lorazepam drug has a differential effect on the monitoring and the control processes involved in a learning task. The implications of these findings are discussed within the theoretical framework of metacognition.

Dose effects of triazolam and scopolamine on metamemory.

“…In previous studies with different paradigms, neither benzodiazepines (Izaute & Bacon, 2005; Massin-Krauss et al, 2002; Merritt et al, 2005; Mintzer & Griffiths, 2005) nor scopolamine (Mintzer & Griffiths, 2005) impaired relative accuracy measures, suggesting that this aspect of metamemory monitoring may be relatively spared despite reliable impairment in absolute accuracy. We speculate that relative accuracy depends on the participant's ability to assess cues related to individual item characteristics, whereas absolute accuracy depends more heavily on assessment of cues related to the participant's overall current state and competence (including drug-induced impairment).…”

Metamemory in schizophrenia: Retrospective confidence ratings interact with neurocognitive deficits

“…Inclusion criteria regarding antipsychotic treatment strongly differ between studies. While previous results suggested that treatment with lorazepam has no influence on evaluation accuracies of people's judgements of learning (Izaute and Bacon, 2005), it has been hypothesized that second generation antipsychotic agents might reduce metacognitive biases by correcting the interplay between cognitive performance and reasoning abilities or by adjusting the liberal threshold of acceptance . This assumption, which cannot be supported by our results, should be investigated further in studies with drug-naïve patients.…”

The neural basis of metacognitive ability

“…Second, if both performance and metacognitive judgements draw upon the same information, metacognitive accuracy or the ability to discriminate correct from incorrect decisions, always increases as task performance itself increases. Importantly, both these hypotheses have been empirically falsified: for the same level of task performance, judgement confidence may differ considerably between conditions [66–68], and, when performance is held constant using a staircase procedure, metacognitive accuracy varies across individuals [21], and can be dissociated from performance through pharmacological [69], neural [20] and task-based [70] manipulations (figure 3).

Figure 3.Data from a visual decision task demonstrating a dissociation of metacognitive accuracy from task performance.

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