When Lilian Kloft stumbled across a 2015 study showing a connection between cannabis use and susceptibility to false memories, she found herself wondering about the legal implications of the results.
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Kloft and collaborators recruited 64 volunteers for a series of experiments. Participants, who were occasional cannabis users, were given a vaporizer containing either cannabis or a hemp placebo and then told to inhale deeply and hold their breath for 10 seconds.
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Kloft and colleagues designed two immersive virtual reality scenarios involving common crimes. In the first, the “eyewitness scenario,” participants observed a fight on a train platform, after which a virtual co-witness recounted the incident but with several errors, including falsely recalling a police dog that wasn’t part of the altercation. In the “perpetrator scenario,” participants entered a crowded bar and were instructed to commit a crime themselves—to steal a purse.
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When researchers interviewed the participants afterward using a combination of leading and non-leading questions, those who were intoxicated showed higher rates of false memory for both the eyewitness and perpetrator scenarios compared with controls.
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[Study coauthor Elizabeth Loftus] says that the team’s study should prompt people to think about best practices when it comes to intoxicated witnesses.
