Earleywine and his colleagues studied 57 users, 30 male and 27 female. Half were given material to read suggesting that marijuana damages the brain; the other half read a research summary suggesting that the drug had no long-term negative cognitive effects. Then, all participants were asked to take cognitive tests after abstaining from marijuana for at least one day. (More on Time.com: See photos of cannabis conventions)
There was a marked difference in results — interestingly, between men and women. Men who got the negative information about marijuana performed worse than men who didn’t, but the women who were faced with stereotype threat actually scored better on tests of verbal skills and memory than women who weren’t given negative information.
Time: Are Stoners Really Dumb, or Do They Just Think They Are?