Saturday, November 7, 2015

How accurate is human memory?

Creative Memories

I recall the time our house was bombed by the Germans. Actually, I don’t. But I do recall my mother telling the captivating story. We love stories—especially stories that inspire us by overcoming great odds or keep us in suspense as to the death-defying outcome.

From time to time a famous person tells a tale that stretches credulity and seems fit for a party or a pub rather than a place of leadership. We want people we can trust. If they lie about their past, won’t they lie to us about important matters?

For decades, psychologists have published studies that plumb the limitations of human memory. Since Bartlett published his famous work in 1932, we have been suspicious about the accuracy in human memory. To paraphrase, Bartlett explained that the processes of relying on memory to help us adapt to life events also lead to errors.

A few years ago (2012), psychological scientist, Daniel Schacter provided a helpful summary of three factors involved in the way memories are distorted as a part of “Adaptive Constructive Processes.”

Three Factors Influencing Accurate Memories

1. The misinformation effect.

This is the effect demonstrated by the research of Elizabeth Loftus and her colleagues. When information is presented to us after an event, that recent information can distort the original event memory. Simple questions of eye-witnesses are enough to introduce information into their memories of things that were never present. 

Deliberately providing misinformation also distorts memories. Numerous studies have confirmed the misinformation effect in both lab work and in live-action events. Unfortunately, false memories can be planted that contain elaborate details about personal experiences that never happened. 

Loftus commented on the problems inherent in autobiographies and memoirs when she wrote about attacks on Edward Teller’s story and suggested we could “appreciate it not as a deliberately self-serving untruthful chronicle but for its possible insights into normal memory-distortion processes. Untruths are not necessarily lies (2012, p. 872).” As Loftus notes, it can be hard to tell the difference between an “honest” and “deliberate lie.”

2. Gist-based memory effect.

We tend to remember the gist of what happened. But we can be stubbornly sure that we learned something that never happened when something new is similar to what we did in fact learn. Psychology students learn this from examples of word lists (DRM; Deese-Roediger-McDermott memory illusion) that contain thematically similar words (e.g., words linked to sleep) and then are presented with a new word they never saw but because it is linked to the theme they are sure of the accuracy of their memory. False recognitions are a part of human memory. Researchers find this “gist” aspect of memory adaptive and commonly found in creative people who can employ the gist of what they have learned to solve novel problems.

3. Imagination inflation.

 Schacter and his colleagues as well as Loftus and her colleagues have shown that imagining something can actually create a false memory that an event really happened. This can be quite alarming if one is focused on the accuracy of the past. But the capacity of our brains to simulate experiences is an adaptive process if we are trying to play out various future options before committing to a course of action. Schacter writes of the “striking similarities between remembering the past and imagining the future (2012, p. 605).”

Our Memories and Our Identities

Intelligent people who write autobiographies and memoirs or write about history based on the memories of others ought to understand human memory and other factors such as the heuristics we rely on when thinking (see Kahneman, 2011). Exercise caution.

Leaders ought to demonstrate a modicum of humility when it comes to recalling their personal history—especially when a self-serving story has the potential for leaving their character open to attack.

Journalists, investigative reporters, and critics also ought to be aware of human memory when attempting to “discover” the truth about one situation or another. When it comes to details, human memory is not perfectly reliable. Care is needed in separating those natural distortions from the deliberate self-serving efforts to deceive others, which can lead to public disasters if not challenged. Aggressive investigators may have the spotlight shone on them if they major in common minor memory errors.

Psychotherapists and counselors ought to know better when it comes to commenting in reports on the memories of their clients. Reporting a client's history as if it were factually accurate is common but accuracy is not consistent with memory research. Similarly, expecting clients to provide accurate details about their life is not reasonable.

Parents and teachers ought to be careful when they are focused on accusing a child of lying. All brains distort events. Memory processes and capacity increase as brains mature. And of course, memory declines in older adults. Children, parents, and teachers along with all humanity do not provide accurate information about their past behavior. Lying is something else.

All of us ought to take care to document important information and store it in more than one place. Relying on our memory for vital information is not reasonable.

Regardless of how well our memory functions, our memories are so important to who we are. Loftus (2003) observations on memory and identity are insightful.

“People’s memories are not only the sum of all that they have done, but there is more to them: The memories are also the sum of what they have thought, what they have been told, what they believe. Who we are may be shaped by our memories, but our memories are shaped by who we are and what we have been led to believe (2003, p. 872).”


We seem to reinvent our memories, and in doing so, we become the person of our own imagination (2003, 872).”

Personal Note

That bomb story my mother told– my guess is a bomb really did explode near our house in England. The other day I saw a published map of bombs that fell in London during the blitz and there were a couple close to our house in West Finchley. My mother recalled being forcibly trapped in the closet under our stairs when the floor buckled upward. Later, another blast caused the floor to settle and she was able to open the door but couldn’t walk for awhile.


Following are my sources. If you are interested in the subject, I recommend reading Kahneman, Loftus, and Schacter.

Kahneman, D. (2011). Thinking, fast and slow. NY: Farrar, Straus, and Giroux.

Loftus, E. F. (2003). Make-Believe Memories. American Psychologist58(11), 867-873. doi:10.1037/0003-066X.58.11.867

Loftus, E. F. (2005). Planting misinformation in the human mind: A 30-year
investigation of the malleability of memory. Learning & Memory, 12,
361–366. doi:10.1101/lm.94705

Schacter, D. L. (1999). The seven sins of memory: Insights from psychology
and cognitive neuroscience. American Psychologist, 54, 182–203.

Schacter, D. L. (2012). Adaptive constructive processes and the future of memory. American Psychologist, 67, 603–613. doi: 10.1037/a0029869

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