Marijuana: effect on nonverbal free recall as a function of field dependence.

The effect of marijuana on the free recall of nonverbal memory was evaluated by presenting 22 male volunteers with line drawings of geometric figures for ten acquisition trials. Each subject served as his own drug control. The study was performed over two sessions with drug condition and list of stimulus materials counterbalanced. Recall varied with drug condition and scores obtained on the Embedded Figures Test. Marijuana reduced recall mainly in those subjects making two or more errors on the Embedded Figures Test, but had little effect on subjects making one or no errors. Intrusion errors were also elevated following marijuana intoxication, but this effect was unrelated to embedded-figures performance . These results are discussed with reference to degree of field dependence and cognitive style.