False memories are pretty easy to manufacture: Scientists can implant them in the brains of their research subjects; law-enforcement officials can unwittingly do it with eyewitnesses. And sometimes, you don’t even need any help — your brain will call up false memories all on its own. As Simon Mankin recently wrote in Scientific American, new research shows exactly what’s going on in the brain as you remember something that never happened.
One popular tool scientists have used to study false-memory formation is something called the DRM task, named for the initials of the scientists who created it. Makin explains:
During the task, participants are presented with a list of words, such as “snow,” “ice,” “winter” and “warm,” which are all related to another “lure” word (in this case “cold”) that is never presented. After some delay, participants must recall as many words from the list as they can, and people frequently report clearly remembering seeing the lure word.
The pattern “tell[s] us our memories are not based on exactly what happened. There’s something more approximate going on, often referred to as a gist memory,” Martin Chadwick, a cognitive neuroscientist at University College London and Google DeepMind, told Scientific American. “Rather than encoding every word, you’re building up an overall concept that you store in memory.”
In the past, Makin wrote, people have explained the DRM task by noting that “similar but not identical meanings are represented by like patterns of activity in the brain, and such overlapping activity leads to false memories.” That explanation, though, has remained a hypothesis — until recently, scientists haven’t been able to identify those specific patterns of activity.
But in a study published last month in the Proceedings of the National Academy of Sciences, Chadwick and his colleagues did just that. The researchers ran fMRI scans on 18 volunteers as they read word groupings for the DRM task, searching for any place in the brain where the response to the lure word (the false memory) looked the same as the response to the other words on the list. They found it in an area in the anterior temporal lobe, which handles semantic memory, or our knowledge of facts, words, and the world around us (as opposed to autobiographical or episodic memory). The specific chunk they identified was an area toward the front of the lobe, called the temporal pole.
The study authors argue that their finding, which highlights our ability to easily make connections between semantic memories, also illustrates the downside of that ability: On the one hand, we organize information efficiently; on the other, this also contributes to our tendency to misremember things. “Creating the gist is helpful for retrieving true memories,” Chadwick said, “and in most situations that’s fine, but sometimes it will also generate a false memory.” Like everything in life, memory is a trade-off: The better it works, the more chance it’ll backfire.