Is Marijuana Screwing With My Memory?

A new study suggests that weed does indeed mess with our memories, which could pose big problems when the police become involved. Also, is weed screwing with my memory?

My memory has been shaky for as long as I can remember, which… um, what was I saying? Where even am I right now? 

Anyway, I’ve long suspected that my constant weed consumption has at least something to do with my inability to string together times and places. Instead, my existence feels like a malleable fog, crammed with what I think are meaningful experiences and genuine feelings, but not necessarily organized in any particular order.

It caught my attention, then, when I stumbled upon a study published in February, which suggests that being stoned significantly increases our susceptibility to forming false memories (a claim backed by science), and that those false memories can be used by law enforcement to wrongly charge people for crimes. 

By false memories, I’m talking about memories that stem from faulty inferences from our actual experiences, or from external sources that supply misleading information, which we then accept as real. For example, you may remember your quarantine partner eating a Hot Pocket last Friday because the box is almost empty, but in reality, you simply sauntered back for seconds while you were super stoned, and therefore, inferred that they must have had one, too.

The researchers came to the conclusion that weed makes us more susceptible to these kinds of memory lapses by recruiting 64 volunteers and sending them through several experiments. To test spontaneous false memories that arise from our own inferences (as opposed to outside sources), the researchers employed the so-called Deese-Roediger-McDermott Task, a false memory paradigm in which subjects are presented with a list of related words (e.g., plate, fork, spoon) and then tested on their recognition of those words. 

In many cases, learned words end up being mixed in with new related words (e.g., knife) that the volunteers falsely assume they were also asked to memorize. In this experiment, the researchers found that, when high, volunteers were much more likely to bring up somewhat related and even totally unrelated words (e.g., fern) as if they belonged to the original list, suggesting that being stoned can basically encourage our minds to come up with random shit out of nowhere.

For a more realistic approach to testing memory and exploring how forming false memories can have a real-life impact (particularly when it comes to policing), the researchers also thrust their volunteers — half of whom were stoned — into virtual reality. In one simulation, the volunteers witnessed a fight on a train station platform, and in another, the volunteers (while in VR) actually stole a handbag from someone at a bar.

Immediately after each simulation, the volunteers were interviewed, during which their interviewer asked leading questions laced with misinformation, an attempt to replicate how witnesses to crimes are often interviewed by police. They found that, when asked about details that never appeared in the simulation, the stoned group was much more likely to say something like, “Yeah, that totally happened.” 

In other words, high people are more likely to be agreeable.

“For me, the most striking thing from this study — but also combined with a field study I did in Dutch coffee shops [i.e., cannabis cafes] — was that cannabis seems to induce a yes bias,” explains lead author Lilian Kloft, a graduate student in the Department of Neuropsychology and Psychopharmacology at Maastricht University in the Netherlands. “We see this most strongly when people are acutely high, but this effect remained in weaker form when people were sober again. This tendency to say ‘yes’ more in conditions of uncertainty can be detrimental and lead to the reporting of false information.” 

Indeed, a witness willing to corroborate most anything a cop says is one that has no place in a court of law.

And what about if you, like so many others, get pulled in for a crime, which you may or may not have committed, while stoned? This yes bias can certainly work against you. “Our team wants to investigate whether this increased vulnerability for false memories also translates to increased risk to go along with other suggestive information, such as when they’re falsely accused of a crime,” Kloft says. “It would be interesting to see whether somebody who’s high or simply a sober-but-frequent-cannabis-user would be more likely to admit to committing something they never did. “

Going by these findings, co-author Elizabeth Loftus, a distinguished professor of psychological science and law at the University of California, Irvine School of Law, suggests that stoned persons should be categorized as vulnerable witnesses, meaning their accounts need to be taken with care and consideration by police. “The straightforward message here is, all other things being equal, you probably would like to interview people about some experience after they’ve sobered up a little,” she says. 

But she also recognizes that waiting can pose problems, too: “As a general rule, the sooner you can interview somebody, the better, because you want their memory to be as fresh as possible. As time is passing and the memory is fading, it becomes more vulnerable to contamination.”

This is where things become especially tricky, because quite frankly, memory is inherently fickle, and stoned or otherwise, studies have shown time and again that our memories are easily and quickly tainted. And when your flighty memory dictates the sentence that someone may or may not receive in a court of law, the room for error is endless, especially when you add in already-present biases from police and investigators. “Even the most well-meaning of investigators, police or others, can lead people, even when they’re trying not to,” Loftus adds.

Going even one step further, beyond how cannabis consumption and false memories may impact policing, it could also be argued that our unpredictable memories — which cannabis seems to contribute to — could impact other important aspects of our lives, too. Both Kloft and Loftus suggest that the yes bias that comes with consuming cannabis could also encourage people to accept fake news that aligns with their current biases, prejudices and beliefs. “Since we’ve seen that acute cannabis influence impairs our ability to process information, it might be wise to avoid being high during situations where it’s important that we process and remember information correctly,” Kloft says. “For example, when studying or when watching the news, where attention to nuanced details is important.”

All of which is to say, as much as I enjoy tuning out of reality with my bong in hand, I also know that maintaining a sober, discerning mind is crucial in a world of constant news and misinformation. And while curbing my weed intake won’t be easy, it sure beats misremembering everything I see, say or do.