Past experiences can be forgotten by changing the context of the memories, according to new research.
The findings have a number of potential applications focused on enhancing desired memories, such as developing new educational tools or reducing harmful memories, including treatments for PTSD.
Memory theorists have long known that we use the context or situation we are in, including sights, sounds, smells, where we are, who we are, to shape and retrieve our memories. But the purpose of this study was to find out whether and how, if possible, people are able to deliberately forget past experiences.
The researchers showed participants pictures of natural landscapes such as forests, mountains, and beaches, and two lists of random words to memorize. During the course of the study, participants were told to either forget or recall random words shown to them in between images of landscapes.
“We used fMRI (functional magnetic resonance imaging) to track how many people were thinking about things related to landscapes at every moment during the experiment. This allowed us to follow step by step how these images, or the context of their presentation, appeared and disappeared from people's thoughts over time,”says lead author Jeremy Manning, an assistant professor at Dartmouth College in New Hampshire.
Immediately after they were told to forget, fMRI showed that they “suppressed” landscape-related activities in the brain.
“It's like deliberately erasing the thought of your grandmother's cooking from your memory, if at that moment you don't want to think about your grandmother,” said Mr. Manning.
“We were able to physically measure and quantify this process using data from the brain,” said Manning.
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When the researchers asked the participants to recall the list of words they studied, there was no suppression of thoughts associated with landscapes. In addition, the number of thoughts associated with landscapes predicted the number of learned words that they could later recall, which showed an easier forgetting process.
The study was published in the Psychonomic Bulletin and Review.