A - 93 The Impact of Motivation on Neuropsychological Performance in Chronic Cannabis Users.

Objective: Cannabis is one of the most widely used substances, and although the literature shows that it affects users' cognition, it is unclear how much that impact is affected by factors such as motivation. Previous studies utilizing validity measures showed that user motivation to perform well positively impacts California Verbal Learning Test - II performance, which was higher in cannabis users who completed it immediately after a motivational statement (Macher & Earleywine, 2012). In the present study, the authors altered the order of test administration to further delineate the role motivation plays in cannabis user performance on neuropsychological measures.

Method: Participants (48 cannabis users, 23 nonusers) completed a neuropsychological battery, including performance validity measures, with random assignment to a motivational or neutral condition. The test order was altered to evaluate whether a motivational statement had an effect on any subsequent test administered or a lasting effect throughout the battery.

Results: Analyses revealed significant differences in performance, with users in the motivational condition performing better than users in the neutral condition on the Block Design (p = 0.006, partial eta squared = 0.157) and Digit Symbol Coding (p = 0.011, partial eta squared = 0.137) subtests of the WAIS-III (both indicating large effect sizes). Nonusers in the neutral condition performed better than nonusers in the motivational condition on multiple subtests.

Conclusion: Results indicate that cannabis users exposed to the motivational statement performed better than those given a neutral statement on several neuropsychological tests. Findings suggest that cannabis users can demonstrate better cognitive performance when sufficiently motivated.