Whether you call it marijuana, pot or weed, you probably have your views on the drug.

Marijuana is firmly established in pop culture, and many states have begun to legalize its use both medicinally and recreationally. But some people aren’t entirely sold on cannabis.

Researchers at a university in the Netherlands are among the skeptics. They say they have found a link between THC, the psychotropic component that gives users the euphoric feeling, and an increased risk for “false memories.”

Scientists say people can create memories of events that never took place and firmly believe them to be true. Previous studies have shown those who smoke marijuana on a daily basis could be at risk for a number of cognitive problems, including impaired learning ability and poor attention to tasks.

To test their theory about false memories, the researchers gave cannabis to one group of participants and a placebo to another group. Those under the influence of THC did not score well on a test consisting of remembering a number of words on a list.

More interestingly, the scientists created a virtual reality experience for the participants in which they either observed or participated in a simulated fight inside a train station. Those with pot in their system were shown to be much more likely to misconstrue the virtual scuffle. One week later, the same groups were brought in sober and the group that had consumed pot earlier was still disposed to their false memories.

Researchers said this information serves as a warning to those like criminal investigators who rely on eyewitness accounts. Your witness may believe they saw something, even if it never really happened.