Everyone lies, whether consciously or not. But if we could put aside moral concerns one moment and watch what happens when you tell a lie, what would we learn about ourselves? What happens in the brain later, when you try to access the memory of your deception? According to a new study from Louisiana State University, the way you remember a lie may be strongly affected by the way you lied in the first place.
The study looks at two kinds of lies, false descriptions and false denials. It also examines the different cognitive processes that we use to store and retrieve them.
A false description is a deliberate flight of the imagination, in other words, details and descriptions that we invent for something that didn’t happen. It turns out that these type of lies were much easier for test subjects to remember.
Lies, Memory and Cognition
“If I’m going to lie to you about something that didn’t happen, I’m going to have to keep a lot of different constraints in mind,”
said LSU Associate Professor Sean Lane. False descriptions, he explained, stay more accessible and more lasting in our memories because they strain our cognitive power.
A liar needs to remember what they say, but also to monitor how plausible they seem, the depth of detail they offer, and even how confident they seem to the listener. If a listener doesn’t seem to be buying what they are saying, they must adapt the story on the fly.
“As the constructive process lays down records of our details and descriptions, it also lays down information about the process of construction,” Lane said.
In summary then, false descriptions take work, so we remember them well. It is exactly due to the effort needed to make them up we can recall them. When subjects in Lane’s study were asked to recall their own false descriptions 48 hours later, memories were mostly accurate. They remembered what they said, and they remembered that what they said was inaccurate.
Tell me Sweet Little Lies
The same does not hold true for false denials. This kind of lie, which is when you deny something that actually happened, is usually succinct, and its cognitive demand is therefore much smaller.
“I’m not constructing details. But I’m also not going to remember the act because there’s not much cognitively involved in the denial,” with a false denial, Lane said. His test subjects had a hard time recalling their own false denials after 48 hours.
The results have implications for forensic interrogation, where suspects typically undergo a series of rapid-fire questions. A guilty suspect would be more inclined to forget a false denial, and so would be more likely to contradict himself on the same information later.
Unfortunately for innocent suspects, there are also implications. Test subjects had a hard time remembering if the denials they’d made were true or false. This same memory problem might plague suspects who are asked to make repeated truthful denials.
The Illusory Truth Effect
This is related to the “illusory truth effect,” the concept that hearing false information repetitively will make it seem truthful, simply because it’s familiar.
“They’re telling the truth, they’re denying, but later this thing seems familiar,” said Lane. “They’re confusing the familiarity of the repetition [with the truth], not realizing that those repeated denials are what makes it seem familiar 48 hours later.”
The logical conclusion is that telling the truth can in fact lead to a false memory. A woman who repeatedly denies being present at the scene of the crime, for example, might actually begin to imagine that scene, including where it was, what it looked like, and who was present, even if she was never there. It feels strangely familiar to her, and because the repeated denials have slipped from her memory, she can’t explain why.
False memory, a well-documented phenomenon, has been researched extensively by Lane all through his career. In a courtroom, a false memory can be disastrous. Now, among other studies like this one, Lane offers forensic investigators a deeper insight into this peculiar behavior.
How you lie affects what you remember
Kathleen M. Vieira, Sean M. Lane
Journal of Applied Research in Memory and Cognition, online 3 June 2013