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What’s Wrong with Inaccurate Memory?

The mistakes we make when remembering also reveal underlying accuracies.

Computer code that is 99.3% accurate is wrong. But should human memory be held to that same standard? The next time we hear about inaccurate or fabricated memories, we need to ask: In what ways were the memories wrong? Chances are, there is a lot more accuracy than inaccuracy. And the inaccuracies can probably be specified and explained.

A wealth of literature demonstrates the fallibility of memory for events we have directly experienced. Expectations prior to the events and questions afterwards can alter our memories. We also forget a lot. But juxtaposed with these repeated demonstrations of memory’s malleability is the contradictory finding that some memories (for example, joyous or traumatic memories) can remain virtually unchanged and verifiably accurate for decades. In fact, oral testimony about well-documented events has been used to correct inaccuracies in the historical record. How can we reconcile this contradiction between memory’s unreliability and its remarkable ability to retain our experiences?

One way to answer that question is to specify exactly how memory is wrong, developing a taxonomy of memory’s mistakes. In one study of mine, participants were required to 1) describe a personal memory they knew was inaccurate in some way, 2) specify what was not accurate, and 3) provide evidence to support the assertion of inaccuracy. My orientation was that of a human naturalist, in the words of Marcel Proust, trying to identify the different aspects of memory inaccuracy.

Most of the memories described in this study were of ordinary events. With a few exceptions, the events were not profoundly traumatic or deeply intimate or overtly life-changing. Many events were consequential but within the realm of normal life: athletic injuries, the death of an aging grandparent, the birth of a sibling, moving to a new house, visiting one’s mother in a hospital. Some events were seemingly inconsequential: playing with cousins, fishing with an uncle, shopping with a friend, a family vacation.

Participants verified the inaccuracy of the memories primarily in two ways: with documented facts (medical records, journal entries, actual physical measurements, photographs, and artifacts) and with validation from parents or other older witnesses (parents, relatives, and neighbors). Another method for verification was the implausibility of the recalled events (for example, playing baseball in Cleveland in January).

What kinds of mistakes were made? Most of the committed mistakes were composite images. Specific images from different time periods were overlaid on one another, as in superimposed imagery. People could be inserted into scenes in which they were not present. The people were remembered accurately and the locations were remembered accurately, but the people were not placed in the correct locations. Ordinarily, this may not be a serious mistake, but in a legal setting, it can be.

General knowledge about people could also create mistakes within a specific memory by intruding into that memory. Suppose we usually go hiking with a cousin, but one time we went with a neighbor. When recalling the day we went hiking with our neighbor, the accumulated memories of hiking with our cousin might intrude into that single instance, and we might remember hiking with our cousin instead.

Other errors involved exaggeration of some sort. Events were remembered as taking longer than they actually did. People, objects, and rooms were remembered as larger than they actually were. Some mis-memories of events were also created by photographs or retold family stories. In a couple of cases, people remembered dreams as actually occurring.

One resonant conclusion from this research on mistaken memories is that very few personal memories are simply made up – or fabricated. Mistakes of commission usually result from blending memories whose components accurately represent original experience. Even mistaken memories represent much of the original experience accurately.

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