Scopolamine and sustained retrieval from semantic memory.

Two experiments were conducted to examine the effects of 0.9 mg oral sco polamine on continuous retrieval of items from natural semantic categories. In experiment 1, scopolamine increased the frequency of item repetition, but had no effect on the number of items subjects could retrieve, or the number of items retrieved per retrieval cue. Experiment 2 introduced a variant of this task where subjects could either retrieve items freely using any preferred strategy, or were constrained to a single retrieval strategy. Again, scopolamine did not impair retrieval of items from semantic categories. It was argued that these negative results are unlikely to be the product of low experimental power, and that the data are consistent with the view that the effects of scopolamine are limited to information acquisition, at least in healthy young subjects.