April 9, 2015

Remember that Memory is Selection, not Retrieval

By Dr. Ken Broda-Bahm: 

9349427_mIf you’re outside in the dark, maybe aided by a little starlight or moonlight, you can probably see your surroundings a bit dimly: You can’t see everything, but hopefully you see enough that you don’t stumble. Now, add a flashlight. The path you’re pointing the light at is now quite bright, but everything else outside the flashlight’s beam has been lost to darkness. Human perception is a lot like that flashlight: You are focusing your attention like the flashlight beam, noticing some things but only at the cost of ignoring everything else. You aren’t just taking everything in. The act of noticing some things also entails the act of ignoring others. As a result, perception is selective, constructed, and decidedly not neutral. 

Memory, it turns out, is the same. We like to think of our memories as a repository or bank: We store our experience, and then retrieve it later, as long as it hasn’t degraded in the meantime. But new research continues to show that memory isn’t like that analogy of a leaky bucket. Instead, it is more like the flashlight in the darkness: It recalls some things, but only at the cost of losing other things. Recently, a team of neuroscientists from Cambridge University (Wimber et al., 2015) published a study with the unwieldy title, “Retrieval Induces Adaptive Forgetting of Competing Memories Via Cortical Pattern Suppression.” The simpler version: In order to remember some things, we need to forget other things. In one of the first studies to show this, the researchers trained participants on specific word-picture pairs. Then they used brain scans in order to map out specific activity patterns while the participant recalled those word-picture pairs. With that map in hand, the researcher next asked participants to repeatedly recall a particular word-picture pair. What they noticed is that as that memory was favored and strengthened, the other competing memories were suppressed. More simply, “Remembering a past experience can, surprisingly, cause forgetting.” Because remembering induces a process that limits distraction, that selectivity serves a purpose. “This form of forgetting,” they add, “is considered to be adaptive because it reduces future interference.” These results, as well as the broader point, carry some important implications for how we handle that critical variable of memory in trials.

The main implication of this research is that, when a witness or a juror thinks back on what they’ve seen and heard, they aren’t drawing from a perfect record that is lodged there in their brain. They aren’t even drawing from an imperfect record. Instead, they are constructing, selecting, and rearranging. “People are used to thinking of forgetting as something passive,” Dr. Michael Anderson, one of the study’s authors, is quoted in Psyblog, “Our research reveals that people are more engaged than they realize in shaping what they remember of their lives.” Forgetting is functional to the extent that it leaves the brain with a manageable amount of information. To use an example shared by Psyblog’s Jeremy Dean, we manage to remember where we parked our car this time, only by forgetting all of the places we have previously parked it. If we remembered them all, it would be far more difficult to actually find the car. 

The law, of course, is still wed to much simpler views of memory: A witness is considered more or less accurate based on the completeness of their memory. While it will probably be of no avail to try to introduce neuroscience in order to give jurors or judges a more nuanced view of memory, there are still a few ways that this constructive understanding of memory can inform your approach in litigation. 

Questioning Witness Testimony

The study provides empirical support for the practical obversation that there is no such thing as a perfect witness. As clear as the recollections may be regarding the central events, there will be gaps around the edges. For jurors who are still – inaccurately — thinking of memory as a kind of camera or recording device, those gaps will provide reason to question the credibility of the testimony. Nearly every witness, at least every honest witness, is going to have those gaps. And for those who aren’t honest, a claim of perfect recall can provide reason for suspicion.

Supporting Witness Testimony

When jurors are able to look at memory a little more realistically, those gaps won’t look as suspicious. In contrast, it can be both intuitive and credible to note that a witness doesn’t remember everything because he was focused on what was most important. “Q: Why don’t you remember whether the assailant was wearing a hat?  A: Because I was looking at the gun.” Of course, a blindness toward details that are important, like a face, can be a problem. But a failure to recall the nonessential details can be presented, not as a weakness in the witness, but as evidence of focused attention.

Understanding Juror Comprehension 

Witnesses aren’t the only ones in the courtroom who are relying on recall. The jurors, for their part, are asked to just take it all in and not talk about it until deliberations. They have to recall it in order to use it in reaching a verdict. But experienced trial lawyers, as well as those who have ever watched a mock trial, know that jurors don’t take it all in. Instead, their recall is tremendously selective. If you observe a mock trial deliberations, you’ll see that some details are entirely missed while others are emphasized way out of proportion. Viewed in light of these research results, that isn’t a failure of memory. Instead, it is just a natural by-product of the way we pay attention and the way we recall. Jurors will remember and use some things, and they will ignore and forget other things. Instead of trying your case in the Quixotic belief that they will ‘get it all,’ focus your strategy on the broad themes jurors are most likely to be left with when the other details recede.

For the legal persuader, ultimately it helps to see perception and retention as a flashlight in an otherwise dark space. You might be filling that space with evidence. But in the end, the question is, “What do you want that light to shine on?” 

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Other Posts on Memory: 

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Wimber, M., Alink, A., Charest, I., Kriegeskorte, N., & Anderson, M. C. (2015). Retrieval induces adaptive forgetting of competing memories via cortical pattern suppression. Nature neuroscience18(4), 582-589.

Image Credit: 123rf.com, used under license

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