Kowal · Psychopharmacology 2015 · Randomized, double-blind, placebo-controlled between-groups trial · n=54

Cannabis and creativity: highly potent cannabis impairs divergent thinking in regular cannabis users.

Cited 55 times in the scientific literature.

Level 2 - randomized trial

Individual double-blind randomized controlled trial

PubMed 25288512 · doi:10.1007/s00213-014-3749-1 · record verified 2026-08-26

What was done

Researchers evaluated the acute effects of vaporized cannabis on creative performance in regular cannabis users using a randomized, double-blind, between-groups design. Participants received a low dose of delta-9-tetrahydrocannabinol (5.5 mg THC; n = 18), a high dose (22 mg THC; n = 18), or a placebo (n = 18). Creativity was measured using the Alternate Uses Task (divergent thinking) and the Remote Associates Task (convergent thinking).

What was found

Participants in the high-dose THC group performed significantly worse on the divergent thinking task compared to both the low-dose and placebo groups. The abstract reports no effect from the low dose relative to placebo, but does not provide exact numerical scores, test statistics, or specific results for the convergent thinking task.

Why it matters

Contrary to widespread anecdotal belief that cannabis enhances creativity, acute administration of low-dose THC did not improve creative tasks and high-dose THC impaired divergent thinking.

Limits

The sample size was small (18 participants per group; total n = 54). The study tested only regular cannabis users, so results cannot be generalized to cannabis-naive or infrequent users. Numerical data, effect sizes, and results for convergent thinking were omitted from the abstract.

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