Scopolamine state-dependent memory processes in man

Scopolamine state-dependent learning was investigated in man using four learning and recall tasks. Twenty-eight subjects performed the four tasks on the first day of the 2 day experiment under either the influence of the drug (5 μg/kg of scopolamine administered IV) or a placebo and tried to recall the material on the second day in either the same or altered drug state. State-dependent learning theory predicts that those subjects in the same drug state on both days should recall more material than those who had their drug condition changed. Results confirmed this prediction for the two recall tasks which did not involve recall cues or prompts but not for the tasks involving memory acids. This implies that the drug state has memory cueing properties of its own and that recall can be enhanced either by restoring the drug state which existed at the time of learning or by providing external prompts.