A recent study in Learning & Memory has some important implications for human factors practitioners. What they found probably won’t surprise you, but might not be something you have considered before.
Most theories of memory assume that representations are strengthened with repetition. We recently proposed Competitive Trace Theory, building on the hippocampus’ powerful capacity to orthogonalize inputs into distinct outputs.
We learned in our first human factors or psychology course that repetition increases the strength of a memory. But as always, the devil is in the details. Memorizing lists of random numbers or words is not what we do in real life. We are encoding much bigger and broader concepts or experiences. But the scope of these concepts and experiences is too much information to encode. So we focus on the most important parts. That makes sense as a strategy.
But when we are using repetition as our encoding strategy, repeating these important details over and over again, there is a catch. While those few important details get encoded very strongly and become long lasting and easily recalled, the rest gets lost. The memory ends up much narrower than we might like.
I can see a few critical flaws in this phenomenon that we need to be aware of. If we are designing systems that present information to users either as part of training or ongoing use, we need to recognize that details will be lost. Depending on the size of the concept, it could be MOST of the details that are lost. And then it gets worse. When users are recalling an experience, for example, their brains need to recreate a story around it. It is simply the way we are wired. So details get added. Just not necessarily the details that were really present during the initial encoding. And this happens under the surface, so users don’t even realize that some of the details they are remembering and that seem so real were added from our exemplar stereotype of the typical case.
Now imagine that the user is an eyewitness at a trial being cross examined by an attorney. The witness may legitimately recall the important factors that are relevant to the case. But the objective of the opposing attorney is to undermine the witness’ credibility. So all he has to do is ask about a few details, get the witness to remember something incorrectly for which there is some physical evidence, and point out the contradiction to the jury. They generalize this error and assume that all of the witness’ testimony is unreliable. Reasonable doubt established. Case closed.
Here is a more fun example. Imagine you are a parent and you are questioning your 7-year old daughter about the broken lamp. You are pretty sure she is lying about it and rather than just make the assumption and look like an unfair tyrant, you want to catch her in a clear fib. So you just ask about some details that she probably didn’t think much about. The story telling instinct jumps to the fore and something interesting, fanciful, and easily falsifiable comes out. Case closed. Manipulative perhaps, but effective.
I am really interested in your thoughts on this one. Do you have memorization strategies that give you a better trace of the details? We also learned in our first course that elaboration is better for encoding complex memories. But just how much elaboration can we expect from our users? Especially for details that might not seem relevant at the time.
Image credit: Brad Shorr