False memories of committing a crime can appear to be real when retold to others, scientists have said.
Researchers from University College London have found that people cannot tell whether a memory being recounted by someone else is fake or not.
The team said the findings, published in the journal Frontiers in Psychology, demonstrate manipulating memories appears to be easier than first thought.
Study author Dr Julia Shaw, of UCL Psychology & Language Sciences, said: “Legal professionals and police officers need to realise how easy it is to manipulate someone’s memories.
“Judges in particular should never assume that they can tell when someone has a false memory, and should consider the entire process to see if there was any risk of contamination of a defendant or witness’ memories.”
The study builds on previous research from 2015 where Dr Shaw and her team managed to implant false memories of committing a crime on their test subjects using a combination of leading questions, suggestive tactics, and visualisation techniques.
For the current research, the team showed the videos from the 2015 study, where the test subjects recounted false memories of a crime which they believed to be real, to a new group of participants.
When asked if the person was describing the crime which actually happened or not, the participants were only 53% accurate with their answers, indicating they were no better at identifying false memories of committing a crime from real ones.
The participants were just as likely to watch someone recount a genuine memory and incorrectly identify it as false, in addition to mistakenly believing false memories to be true, the researchers said.
Dr Shaw added: “Everyone thinks that they couldn’t be tricked into believing they have done something they never did, and that if someone were telling them about a false memory, they would be able to spot it.
“But we found that actually, people tend to be quite susceptible to having false memories, and they sound just like real memories.”
She said the current study shows the importance of ensuring criminal proceedings are done correctly.
Dr Shaw added: “The questioning process should be evidence-based, to reduce the risk of implanting false memories in people being questioned by the police.”