Our memory isn’t as reliable as we’d like to think it is.

Watching someone perform a task can trick our minds into thinking that we’ve done it ourselves, according to research published in the journal Psychological Science.

In the study, participants who watched a video of someone else performing a simple task—like putting a match into a box or shaking a bottle—were more likely to think that they performed the action themselves when asked about it two weeks later.

“These findings were a huge surprise,” explains Gerald Echterhoff, Ph.D., professor of social psychology at University of Muenster, Germany. “We began the research with a focus on imagination as a source of false memory but in examining the effects of observation, we realized we discovered something more novel.”

A discovery that has dangerous real world applications. “Some of the consequences could be detrimental to our health and well-being,” states Echerhoff. Imagine witnessing your wife taking a pill and thereby, forgetting to take your own. Or watching a TV character turn off the stove, thus not doing so yourself.

More research is needed to explain these findings but researchers suspect that sometimes, humans tend to imitate the behaviors of others. “This would occur spontaneously and without our awareness,” explains Echterhoff, which makes these findings even more disconcerting. “Simulation is good when it helps you predict someone’s next action, or to learn how to do things, but this could be an unfortunate side effect.”

Good news: Don’t worry about this happening on a constant basis. “We don’t always go around mistaking the actions of others for our own. Just remember that your memory isn’t always reliable,” warns Echterhoff. “It’s good to have an informed doubt or informed skepticism about your memory performance, so you don’t easily trust whatever comes to your mind as true.”