In the U.S. and across the world, reliance on witness testimony and interrogation techniques leads to the conviction and incarceration of innocent people. It is generally assumed that only real criminals admit guilt or that a confident witness could be fully trusted. Psychologists have found, however, that memory is far less reliable than we once imagined.

False memories can take many forms; you may have a distinct memory of locking the door or telling your friend something when these events never happened. They can be partially true, such as remembering what you ate for breakfast yesterday instead of today. However, they can also be entirely false, like an imagined experience of being lost in a mall when such an event never occurred. Ariel James, an assistant professor of cognitive psychology at Macalester, helped to describe memory.

“False memories are when you remember something that didn’t happen,” James said. “It’s not lying; it’s truly thinking that you remember something that did not in fact happen the way that you remember it. It may not have happened at all.”

According to James, this happens because human memory is reconstructive. Our brains call on background knowledge, other memories, imagination and dreams to fill in the gaps.

“Sometimes it’s hard for us to tell apart what we’re actually remembering versus other information that we have,” James said. “There are all of these different sources that give us information, causing what we call ‘source confusion’ errors; not knowing where the memory came from. If you think the memory came from your experience and it didn’t, that’s where a false memory happens.”

Psychology professor Brooke Lea is the director of the cognitive science concentration at Macalester. 

“Every memory is subject to some amount of distortion,” Lea explained. “You and I can witness the same car crash, but have different memories of the same event.”

Ordinarily, these are harmless errors, but in important situations such as police interrogations, false memories may cause disastrous consequences. Under the assumption that no innocent person would admit guilt to a crime they did not commit, police have the legal ability to lie to suspected criminals. They can claim to have evidence that doesn’t exist, or state that the suspect failed a polygraph in order to pressure someone into admitting guilt. By asking leading questions or suggesting that something happened, interrogators can plant a “seed” of a false memory which the brain can flesh out to create an invented narrative.

Cognitive psychologist Elizabeth Loftus created an experiment where participants were asked leading questions about childhood memories, supposedly supported by a family member. At least 25% of participants not only confirmed the memory, but added surprising amounts of vivid detail. 

“When you feed people misinformation about some experience that they may have had, you can distort or contaminate or change their memory,” Loftus said in an interview with NPR.

Eyewitness memory is also less reliable than many would hope, and has contributed to wrongful convictions. Intuitively, most people assume that the more confident someone is, the more accurate their memory should be. However, according to research out of Stockholm University, the opposite seems to be true. More confident responses corresponded with lower accuracy.

“The more vivid memories are, the more we believe people. … The disturbing news is that we can be quite sure that we saw faces that were never there,” Lea said. “Studies found that the more confident someone is, the less likely [their testimony] is to be accurate. … It’s surprisingly easy for people to have vivid memories of events that never actually happened.” 

The Innocence Project is a non-profit organization that exonerates wrongly convicted individuals through DNA testing and analysis. According to their research, Innocence Project clients have spent at least 3,670 hours in jail without reason. Some of these people had confessed guilt to crimes they never committed and later evidence proved their innocence. Others had been convicted after witnesses confidently testified against them (under oath), claiming to have seen events that were later proven incorrect or entirely made up.

According to an article in Healthline, suggestion, misinformation, time and emotional settings may magnify vulnerability to memory distortion and false memory formation. Although memory will never be foolproof, Lea suggests taking notes or corroborating memories with evidence when possible to avoid mistakes. He recommends calling a lawyer upon run-ins with the police.

“Therapists, interviewers, police interrogators should be aware of how influential they can be. … People can make themselves remember things or fill things in,” James said. “It can end up generating something completely out of thin air.”

We remember first impressions, but preconceived notions about people can also impact our perception and memory retrospectively. 

“It’s very easy for us to feel confident in our memory, our judgements, our intuitions about people,” Lea said. “[But] we should be more modest about what we think is true.” 

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