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The Neuroscience of How We Intentionally Forget Experiences

The context of a memory is central to forgetting good and bad life experiences.

Bruce Rolff/Shutterstock
Source: Bruce Rolff/Shutterstock

Researchers at Dartmouth College have discovered that both good and bad memories are inherently linked to the context in which you experience the memory. As an example, hearing Bruce Springsteen’s song, “Born to Run,” on the radio could remind you of the romance and limerence of your first true love, or it could remind you of the nerve-racking flashback of getting your first speeding ticket.

Using a new functional magnetic resonance imaging (fMRI) brain scanning technique, the researchers were able to identify that in order to intentionally forget past experiences, people change how they think about the context of those memories and the contextual triggers that evoke flashbacks.

We all know from life experience that anytime you’re brokenhearted, hearing a song that reminds you of that person brings back a wave of memories and nostalgia that would otherwise lay dormant. In order to intentionally forget this person, you would most likely delete any playlists or songs that open the floodgate of memories associated with your ex-partner. This new study pinpoints the underlying brain mechanics of how we do this type of intentional forgetting.

The May 2016 study, “A Neural Signature of Contextually Mediated Intentional Forgetting,” appears in the journal Psychonomic Bulletin and Review.

Lead author of this study, Jeremy Manning, assistant professor of psychological and brain sciences at Dartmouth College, and his collaborators from Princeton, found that people can intentionally forget past experiences by performing a “scene drop” in which you basically avoid playing the mini-movie in your head associated with the context of a memory.

The elements that create the context of a situation include: sights, sounds, smells, where you are, who you are with, time of day, the quality of light, etc. Because the contextual representations of a memory might include a wide range of sensory perceptions pertaining to your past—if you avoid thinking about any of these contextual cues, it automatically diminishes your capacity to remember an event. On the flip side, consciously reminiscing about the specific contextual elements can bring back vivid memories of the experience.

For this study, Manning and colleagues created a state-of-the-art brain imaging method that illustrates how people intentionally forget past experiences by changing how they think about the context of those memories as represented by a distinctive neural tapestry. Their new fMRI technique allowed researchers to specifically track thoughts related to memories' contexts. In a statement, Manning said,

"We used fMRI to track how much people were thinking of scene-related things at each moment during our experiment. That allowed us to track, on a moment-by-moment basis, how those scene or context representations faded in and out of people's thoughts over time.

It's like intentionally pushing thoughts of your grandmother's cooking out of your mind if you don't want to think about your grandmother at that moment. We were able to physically measure and quantify that process using brain data."

Remembrance of Good and Bad Things From the Past

In the novel, Remembrance of Things Past, Marcel Proust touches on how the context of a memory is tied to a scent that is also directly linked to the specific neural networks that Manning et al. were able to illustrate in their recent study.

Proust hones in on the power of a specific smell to trigger vivid flashbacks to forgotten childhood memories. After the protagonist in this story dips a madeleine biscuit into a cup of tea, a wave of memories are immediately brought back into consciousness with their original intensity. Researchers call this “Proustian memory effect.” Childhood memories linked to scent stay with people throughout life.

Richard Bergland used with permission.
The Demirjians in Quogue circa 1975.
Source: Richard Bergland used with permission.

Do you have a smell that triggers a very strong flashback to a good or bad experience? I’ve heard combat veterans with PTSD describe that the smell of gasoline can be such a strong trigger of the atrocities they experienced during war that it makes it impossible for them to fill up the tank at their local gas station. For me, the smell of Coppertone has always brought back idyllic childhood memories of clear, bright blue skies, sunshine, and the joy I felt whenever my family spent time with my parents’ closest friends, the Demirjians, in Quogue every summer.

When my father died, I went through all of his Kodachrome slides and had them made into prints. I keep the photo you see above on a dresser because it never fails to brings back memories of a very happy time during my youth. As I sit here typing this, I also just sprayed on some Coppertone to have these joyful memories come back to life more tangibly, which they have.

Conversely, after reading this study, I was thinking of contextual situations that would bring back terrible memories for me—the bad memories, that I’ve intentionally forgotten. The first thing that came to mind was the house that my family lived in when my parents’ marriage began to unravel and their divorce took on War of the Roses dimensions in the late '70s. Because I purposely don’t have any photos of this era, I typed "2496 Beacon Street" into Google Earth to see what would happen...

Courtesy of Google Earth
2496 Beacon Street
Source: Courtesy of Google Earth

Well, as the satellite image zoomed in on Massachusetts and got closer and closer to Chestnut Hill, I instantly felt sick to my stomach. On a visceral level, I remembered exactly what it felt like to be a tormented fifteen-year-old kid again. Within milliseconds of seeing the satellite view of the house—with the dormer windows on the top floor where I slept—I had about a dozen specific horrible memories come rushing into my mind, as if it was yesterday.

This street scene might look bucolic and inviting to the average onlooker, but, for me, this location triggers feelings of PTSD. The reservoir, the curve of the road, and the little cul-de-sac where I would get picked up by car pool are all contextual cues directly linked to a slew of very bad childhood memories. I can see my bedroom window from this birds' eye view and it makes me want to puke.

Yuck! I won't be looking at images of 2496 Beacon Street again for a very long time. In my mind, this is anecdotal evidence that corroborates the empirical findings of the latest brain imaging study.

Conclusion: You Can Choose to Forget Memories by Forgetting Their Context

The groundbreaking new findings from Dartmouth on how we intentionally remember, or forget, have a wide range of possible applications. Future research on these findings could lead to more effective ways to encode desired memories, such as developing new educational tools for learning; or help identify better ways to diminish painful memories associated with PTSD. Stay tuned for more on this exciting topic of research.

To read more on this topic, check out my Psychology Today blog posts,

© 2016 Christopher Bergland. All rights reserved.

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