THC, the main psychoactive component of cannabis, impairs visual working memory—the ability to temporarily hold information in mind. In two double-blind, randomized crossover experiments, healthy adults performed a visual working memory task after taking oral THC (7.5 or 15 mg) or a placebo. THC reduced working memory performance (effect size d = 0.65), increased self-reported mind wandering, and decreased the accuracy of participants' awareness of their own task performance. The findings suggest that THC disrupts working memory both by increasing mind wandering and by reducing metacognitive monitoring. The study also demonstrated that short task durations and small sample sizes can mask such drug effects.
A double-blind, placebo-controlled experiment with 24 healthy infrequent cannabis users tested how THC (15 mg oral) affects context-based memory illusions. Participants memorized object pictures on scenes (e.g., a cat on a beach) after THC or placebo. Two days later sober, they discriminated seen objects from similar lures, with context reinstated or changed. THC impaired memory for perceptual details compared to placebo. Context reinstatement increased both correct recognition and false recognition in both conditions. THC did not interact with context effects overall, but post hoc analyses showed THC magnified the context illusion when objects were semantically congruent with their encoding contexts and abolished it when incongruent. Results suggest THC impairs encoding of specific object information more than item-context associations, potentially sparing or increasing distorting effects of context.
Manoj Doss critiques five methodological sins in psychedelic research, focusing on biases from researchers' personal drug experiences and self-experimentation. He argues for integrating cognitive psychology with neuropharmacology and using empirical, behavioral measures to study psychedelics' effects on cognition and memory, aiming to advance a more rigorous scientific understanding of these substances.