Why Do Our Memories Change?
By Mark Fischetti, Scientific American Blog Network
February 10, 2017

Where were you on September 11, 2001, when you first heard about the World Trade Center towers in New York City being hit by airplanes and collapsing? Almost all of us remember clearly where we were, how we heard the news and what images we first saw. Yet research shows that our recollections of past events are typically only about half correct—even though we are convinced that our memory is certain.

This disconnect is explored by Liz Phelps, a professor of psychology and neural science at New York University. Phelps concentrates on how learning and memory are changed by emotions. She explains why our memories can be so malleable in an engaging video called Controlling Our Fears, created by her N.Y.U. colleague Joseph LeDoux, an expert on the emotional brain. The video is the fourth in a series he is putting together with director Alexis Gambis called My Mind’s Eye. (The first episode featured Ned Block on the mind–body problem, the second video was with Michael Gazzaniga on free will and the third was with Nobel laureate Eric Kandel on how neurons in the brain learn and create memories in the first place.)



In the video Phelps explains that our memories can change because each time we revisit them they become vulnerable. When we first lay down a memory, it takes the brain a little while to solidly store the information—a process called consolidation. And every time we subsequently recall that memory, it has to go through a new storage process—another slight delay for another consolidation. During that window, new information can interfere with the old information and alter the memory. Phelps says it is like playing the school game of telephone, where one student tells a short story to a second student, then that person retells it to a third, who tells it to a fourth, and so on. By the end of the chain the story is usually quite different from how it began.


This change in memory has been proved by experiments using drugs in rodents, and in exercises with people. Phelps describes this work in the video. She also notes how reconsolidation might be used to help people control unwanted memories that involve fear or anxiety. The enticing news is that we might someday be able to defuse such painful memories.


For fun, the Phelps interview comes with snippets of a related song that LeDoux recorded with his band, The Amygdaloids, called I Just Want to Forget How to Remember You.