The Myth of Cognitive Decline

“The Myth of Cognitive Decline: Non-Linear Dynamics of Lifelong Learning”1 is certainly one of the most important scientific articles I have read in recent years. Contrary to the commonly accepted notion that cognitive information processing capabilities decline across adulthood, the article makes a compelling argument that older adults’ changing performance reflects memory search demands, which increase as experience grows.

This argument is based on a series of simulations that show how the performance patterns observed across adulthood emerge naturally in learning models as additional knowledge is acquired. The simulations identify greater variation in the cognitive performance of older adults, and also predict that older adults show greater sensitivity to fine-grained differences in the properties of test stimuli than younger adults. In other words, the results indicate that older adults’ performance on cognitive tests reflects the predictable consequences of learning on information processing and not cognitive decline.

Simply put, the more information we have as we age can slow down the retrieval of information and make it more difficult to distinguish differences among items in memory. Here it is wise to revisit the distinction between information availability and information accessibility. Information can be available in memory, but we simply cannot access it. Many times we know we know something, but simply cannot recall it. These are the cases when information is available but not accessible. Frequently, I try to recall some piece of information, say an actor’s name, but just can’t seem to locate it. Sometimes I shall challenge my wife and see if she remembers. Sometimes she does, and sometimes she doesn’t. Sometimes she will come up with a partial cue that leads to the desired memory. I try to resist the temptation to Googling it in these situations as I think these attempts at retrieval aid keeping the memory healthy.  They force us to revisit infrequently visited memory circuits. What is interesting is that long after I have consciously given up the search and resisted Googling it, the desired memory will suddenly pop into mind. This might occur the next day, perhaps even several days later. This is a good example of how a long latency might be mistakenly interpreted as a memory loss.

One might argue that these conclusions are based on simulations rather than on human experiments. Research into this topic is currently underway using humans. The problem with using human participants to research this problem is that it is difficult to control or estimate important variables. In these cases, simulations can actually provide more accurate answers.

There is the observation that cognitive decline really kicks in around 60 or 70. What is the basis for this observation? How can it be explained? Here is the explanation taken directly from the Ramscar article on p. 34: “If a common environmental change like retirement was to systematically reduce the variety of contexts people encounter in their lives, learning theory predicts that the amount of contextual information they learn will drop further, as the background rates of cues in the remaining contexts rise (Kruschke,2 Ramscar et al3). It follows from this that if people were to increasingly spend time in environments where any cues have high background rates already (family homes), any effects arising from their cumulative experience of learning to ignore task irrelevant contextual (background) cues will be exacerbated . In other words because discriminative learning by its very nature reduces sensitivity to everyday context, retirement is likely to make memories harder to individuate and more confusable, absent any “cognitive declines,” simply because retirement is likely to decrease contextual variety at exactly the time when the organization of older adults’ memories needs it most.”

In other words, as you have read in previous healthymemory blog posts, retirement can foster cognitive decline. So retirements need to be active, so that people can continue to grow cognitively and have social engagements in varying contexts. Obviously I am biased, but I think that reading the healthymemory blog and following some of its practices provides a good start.

It is certainly true that there can be pathologies that cause cognitive decline. Unfortunately, what is the normal performance of what are truly healthy memories can be misinterpreted as cognitive decline.

1Ramscar, M., Hendrix, P., Shaoul, C., Milin, P., & Bayan, H. (2014). Topics in Cognitive Science, 6, 5-42.

2Krushke, J.J. (1996). Base Rates in Category Learning. Journal of Experimental Psychology: Learning, Memory, & Cognition. 22, 3-26 .

3Ramscar, M., Dye, M., & Klein, J. (2013). Childrean value informativity over logic in word learning, Psychological Science, 24, 1017-1023.

© Douglas Griffith and, 2014. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Douglas Griffith and with appropriate and specific direction to the original content.


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