You know that time you and your schoolmates stole the teacher's briefcase and made him frantically search the room for 15 minutes? It may never have happened.

A new study from the University of Warwick found that if we're told about a made-up event from our lives — from taking a hot air balloon ride as a child to playing a prank on a teacher — and repeatedly imagine that event occurring, almost half of us would accept that it did.

Read: Memory Is Selective Forgetting: Brain Alters The Past Every Time We Try To Remember It

Researchers worked with over 400 participants who’d had fictitious autobiographical events suggested to them. About 50 percent believed, to some degree, that those events had actually happened, Medical XPress reported. Thirty percent said they "rememberd" the event, and even elaborated on event details and described images, while another 23 percent accepted the fake event to some degree even if they didn't fully embrace it.

Researchers concluded that it can be very difficult to determine when a person is recollecting actual past events because it’s possible that they’re false memories.

Read: Memory Can Be Strengthened Even As You Age: Neuroscientists Explain

"We know that many factors affect the creation of false beliefs and memories — such as asking a person to repeatedly imagine a fake event or to view photos to ‘jog’ their memory. But we don't fully understand how all these factors interact. Large-scale studies like our mega-analysis move us a little bit closer,” said Dr Kimberley Wade in the department of psychology, according to Medical XPress. "The finding that a large portion of people are prone to developing false beliefs is important. We know from other research that distorted beliefs can influence people's behaviors, intentions and attitudes."

Source: Scoboria A, Wade KA, Lindsay DS, Azad T, Strange D, Ost J. A mega-analysis of memory reports from eight peer-reviewed false memory implantation studies. Memory. 2016.

See Also:

Strongest Memories: Why You Remember Experiences Between Ages 15 And 25 So Clearly

Why We Only Remember Fragments Of Traumatic Memories, And How It Can Help Us Treat PTSD Flashbacks