Marijuana enthusiasts may believe cannabis expands their minds and increases their creativity, but science disagrees. According to Dr. Mikael Kowal, a researcher at the University of Leiden in the Netherlands who has investigated the effects of marijuana on creative skills, the drug dulls your ability to think outside the box and also dilutes your ability to recognize your own mistakes.

Kowal has dedicated many years to understanding how marijuana affects our brains, and has previously found, (and his new research confirms) that marijuana users are less able to brainstorm, a crucial skill for creative performance. According to a recent university press release, marijuana interferes with dopamine production in the brain, a hormone which plays a role in learning. According to Kowal, marijuana interfered with user’s creative thinking process and inhibited their ability to recognize their faults.

“'It is important that we gather more knowledge about the effects of cannabis on a person's ability to detect mistakes,” explained Kowal in a recent statement. “This can help with putting together a treatment programme for drug addiction.”

For the study, Kowal had 40 regular marijuana users and 20 non-users conduct a series of experiments to test both their creative thinking skills and their ability to recognize their own mistakes. Results showed that chronic marijuana users were less able to complete the tasks correctly, and less able to recognize their own errors. However, the team noted that marijuana may not affect all individuals the same way; certain factors such as age at which marijuana use began, and individual biological differences, could result in different outcomes among individuals.

Although Kowal’s link between marijuana use and problems seeing mistakes is novel, this is not the first time that he has attempted to debunk the idea that marijuana expands your mind. In a 2014 study, Kowal, alongside a team of other researchers from Leiden University, conducted a similar experiment in which they had 54 marijuana smokers complete creative thinking tasks such as rapidly generating solutions to a problem, or linking a series of similar words with a common theme. Again, high doses of THC had a negative effect on the volunteers' ability to come up with creative solutions.

“If you want to overcome writer's block or any other creative gap, lighting up a joint isn't the best solution. Smoking several joints one after the other can even be counterproductive to creative thinking,” concluded Kowal’s research partner, Dr. Lorenza Colzato in a previous statement.

Drinking alcohol, on the other hand, has been linked to increased creativity, although only when used in moderation.

Read More:

Smoking Marijuana Does Not Improve Creative Thinking, Only The Illusion Of Creativity: Read Here

How Drinking Alcohol Makes You More Creative: Drink Up For More 'Aha!' Moments: Read Here