Study Finds People Who Smoke Weed Are More Likely to Have ‘False Memories’

Even just one hit of weed doubled their chances of recollecting something that didn’t really happen or was different from the way it happened.
Shamani Joshi
Mumbai, IN
smoking weed makes you more likely to have false memories
Photo by Ahmed Zayan / Unsplash

We all probably have that one member of the circle who will get high off their ass, embark upon a journey to securing munchies, and come back with a colourful tale of how they saw a flying dog, tasted rain or got mugged by a monkey. Stoners often swear on the wild stories they tell, even when the general reaction is to dismissively shrug it off with a “Bro you smoked way too much.” But turns out there is some scientific merit to why your friend may be stacking up these tall tales.


A new study led by Lilian Kloft of the Faculty of Psychology and Neuroscience at Maastricht University, in the Netherlands, tried to make sense of the effects of cannabis on our memories, and it turns out that regular toking can tweak the truth. We already know that smoking weed affects memory and can impair an individual's ability to remember even recent events, but this new research finds that people who are high as a kite also formulate “false memories.” This is especially important from a legal point of view in terms of testimonies and memories declared by eyewitnesses at a crime scene.

To gauge how severely cannabis can affect one’s memories, researchers enlisted 64 volunteers and put them through a test involving both, visual lists and virtual reality. In the first test, participants were made to memorise a list of words, then asked to recite them immediately as well as after a week. One group of participants was given THC-activated weed while the other was given a placebo, and based on their answers, researchers realised that those who were stoned, recited more random or unrelated words as compared to those who weren’t.

To verify these findings, the participants were put through virtual reality true crime situations, one as eyewitnesses and the other as perpetrators with half the group doing it sober, while the other half getting high before the simulation. After each simulation, the participants were interviewed with purposely placed misinformation to throw them off-track, such as hinting that a gun was used in a situation where the robber used a knife. Once again, the findings proved that those who were high tended to remember false subjective details, especially when prodded by another person’s perspective. "People under the influence of cannabis show the highest risk for false memories for things or details that are poorly related to the original event," Kloft concluded. "It appears that [cannabis-intoxicated people] have a 'yes' bias when they are uncertain about their memory, which makes them sort of random and unreliable responders."

The team repeated the same tests the following week to see how participants responded once they sobered up. This time around, there was no significant difference in the memory span of those who used cannabis the week before and those who didn’t, showing the tendency of memory to decay over time. The study published in the journal Proceedings of the National Academy of Sciences, therefore comes to the conclusion that smoking weed can cause people to believe things that may not be true, creating the greater need for a system in which an eyewitness’ sobriety is ensured before they recount the situation.

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This article originally appeared on VICE IN.