False memory formation in cannabis users: a field study

Abstract

RationaleCannabis use is widespread and has previously been associated with memory impairments. However, the role of cannabis in relation to false memory production, i.e., memories of events that were not experienced, is less well-understood.ObjectiveThe aim of the current field study was to examine the impact of cannabis use on false memory production.MethodsThe Deese/Roediger-McDermott (DRM) paradigm was used to induce false memories. In this paradigm, participants study word lists that are associatively related to a non-presented word, termed the critical lure. In a later memory test, true recognition rates and false alarm rates toward critical lures and unrelated items are assessed. Memory performance was compared between three groups: regular cannabis consumers who were acutely intoxicated (n = 53), regular cannabis consumers who were sober (n = 50), and cannabis-naïve controls (n = 53). The participants were approached in Dutch coffee shops (cannabis outlets) and cafes and asked to participate in our study. After collecting general information on their cannabis use, they were subjected to the DRM procedure.ResultsAlthough false memory rates for critical lures did not statistically differ between groups, both intoxicated and sober cannabis consumers falsely recognized more unrelated items than control participants. Also, individuals without a history of cannabis use demonstrated higher memory accuracy compared with the intoxicated group.ConclusionIt is concluded that cannabis intoxication and history of cannabis use induce a liberal response criterion for newly presented words for which the level of association with previously learned words is low and uncertainty is high.

Cannabis increases susceptibility to false memory

“…The findings obtained from the DRM paradigm extend and replicate previous findings in several ways. Acute cannabis use did not significantly affect immediate true-recognition performance, or false recognition of critical lures, which was similarly shown in the coffeeshop field study (18). However, cannabis elevated immediate false-memory rates for related and unrelated stimuli (medium and large effect sizes, respectively).…”

“…A highly reliable and common method to evoke spontaneous false memories is the Deese/Roediger-McDermott (DRM) paradigm (15)(16)(17), in which people falsely remember words not actually presented in an associatively related list of words. Research on cannabis and DRM false-memory formation is sparse, but in a recent field study, we compared intoxicated vs. nonintoxicated cannabis users vs. a nonusing control group (18). No statistical difference between groups was found for the acceptance of "critical lures" (associated but nonpresented theme words).…”

“…However, people are not always interviewed immediately following a crime, so it is also imperative to include a retrieval condition in which participants are sober. Given the described findings of cannabis-induced memory impairment (1,18,20), cannabis intoxication was generally expected to result in higher false-memory rates, compared to a placebo condition.…”

Hazy memories

“…The reverse was however true when item and context were not congruent, in which case THC abolished context-based false memories. THC did not affect false recognition of dissimilar lures here, indicating that the response bias observed when tested sober in Kloft et al, (2019Kloft et al, ( , 2020 may perhaps be specific to verbal stimuli.…”

“…In a recent field study conducted in Dutch coffeeshops (Kloft et al, 2019), three groups were subjected to the DRM procedure: intoxicated cannabis users, sober cannabis, and a non-using control group recruited at other public locations (N = 156, between-subjects). No differences between groups with regard to true recognition or false memory for critical lures was detected; however, both groups of cannabis users showed elevated susceptibility to false alarms in response to new, semantically unrelated words.…”