A total of 54 healthy Dutch people (six women and 48 men) in their early 20s who regularly used marijuana were included in this study. “Regular use” was defined as consuming marijuana at least four times per week for the past two years. “Healthy” here meant that the participants did not have significant mental or physical disorders, did not abuse alcohol, were not on any psychotropic medications, and did not use any other drugs recreationally. People who smoked cigarettes were included in the study.
After recruitment, the participants were then randomized to inhale vaporized marijuana that contained one of three levels of THC. The vaporizer they used (a Volcano-brand vaporizer, depicted in Figure 2) had a large balloon attached to it which filled with the vapor, and the participants were asked to inhale the contents of the balloon deeply and hold their breath for ten seconds before exhaling. It’s a pretty big balloon, so it took several inhalations to completely consume the balloon’s contents.
Figure 2: The Volcano vaporizer
The total amount of THC delivered to each participant in the three groups was 22 milligrams (high dose), 5.5 milligrams (medium dose), or almost 0 milligrams (placebo). Acknowledging that not all the THC in the plant is vaporized, and not all of the inhaled THC is absorbed through the lungs, the researchers estimated that the actual doses absorbed were eight milligrams, two milligrams, and zero milligrams, respectively. The participants and experimenters were blinded to what dose of THC was being delivered.
The study participants were then asked to report their subjective feelings six minutes after completely consuming the marijuana. They then completed two tasks to measure their creative thinking 35 minutes and then 60 minutes after consuming the marijuana, and given 10 minutes to complete each task. But ... how can you measure creativity? Well, psychologists, being a somewhat creative bunch themselves, have come up with a few tests to do so.
One of the tests was the Alternate Uses Test (AUT), which measures divergent thinking, an aspect of creativity. The AUT asks people to generate as many as possible uses for a common household items as they can think of in a given span of time. For instance, a pen can write, hold a door open, be used as a bookmark, be melted and molded into a shape, etc. The answers were then rated by two independent reviewers blinded to treatment conditions according to four different criteria: fluency, flexibility, originality, and elaboration. The scores highly correlated with each other, which suggests that the tests were rated reliably.
The other test was the Remote Associates Task (RAT), which is considered a measure of convergent thinking. This task involves giving a group three words and encouraging them to try to find a fourth word that links them. One example is “back, go, light.” The fourth word for this set is “stop.” Since the RAT has “objective” answers, it is easier to come up with a final score for it than the AUT. You just count the number of right answers.
The tests were administered in a random order to each participant to make sure the order of administration didn’t affect the results. Also, after each creativity test, the experimenters again asked the participants to rate their subjective feelings.
This study recruited 59 people who were young, healthy, and frequently used cannabis. Researchers intended to test the effect of cannabis on creativity. Participants were randomized to inhale marijuana which had either high, medium, or almost no THC. After consuming the marijuana, they were administered two tests of creativity: the Remote Associates Task (RAT), which measures convergent thinking, and the Alternate Uses Test (AUT), which measures divergent thinking. Their subjective feelings were also measured throughout the experiment.