According to the Fox News article "Chimps Smarter Than Humans in Memory Test" chimps were able to significantly outperform humans in a simple working memory task. I quote one part of the article in particular:

Matsuzawa speculated there was an evolutionary tradeoff between this kind of sharp memory and the higher mental functions seen in humans, such as our advanced capability for language.

Could this "trade-off" mean that training to improve working memory could cause your brain to adapt to such training at the expense of language and problem solving abilities?

Matsuzawa's 2012 article in Current Biology


5 Answers 5


No. Different parts of the brain are responsible for different functions, and the brain would not spontaneously reorganize based only on a improved WM.

Memory is a huge factor in intelligence, and improving WM would likely result in increased scores on intelligent tests, and in general is a good thing.


Increased prefrontal and parietal activity after training of working memory

  • $\begingroup$ I don't disagree with you, but having some references to back up your assertions couldn't hurt. $\endgroup$ Feb 20, 2013 at 3:52
  • $\begingroup$ I am sure there are references in the field of developmental psychology demonstrating that WM could be a good predictor for general IQ, but I don't remeber them... some specialist in this topic ? Anyway, at the pure logical level, the fact that chimps are better at WM tests is not a demonstration of Matsuzawa's hypothesis. $\endgroup$
    – Cheatboy2
    Feb 20, 2013 at 8:15
  • $\begingroup$ Both the Wechsler scale and the old Binet-Simon test as well as some tests used for clinical purposes have a subtest which is essentially a WM capacity test: remembering rows of numbers, repeating them forwards and backwards. How well people do on this subtest is thus directly related to the IQ score they will get. $\endgroup$
    – Ana
    Feb 20, 2013 at 10:08
  • $\begingroup$ @Ana, the presence of working memory on an IQ test doesn't mean that working memory contributes to language and problem solving abilities (i.e. the higher order thinking skills). Chimps are terrible compared to humans at such things, yet chimps are superior on the working memory task. $\endgroup$
    – Kenshin
    Feb 20, 2013 at 23:17
  • $\begingroup$ @Cheatboy2, what is Matsuzawa's hypothesis? $\endgroup$
    – Kenshin
    Feb 20, 2013 at 23:18

The conclusions drawn in Inoue & Matsuzawa's (2007) study, which seems to be available here, are suspect. First off, the sample sizes (6 chimp, 9 human subjects) are simply too small to draw good inferences about working memory, at least about human working memory, but as I imagine chimps are somewhat expensive subjects, c'est la vie.

Secondly, and more worryingly, the study design itself seems to have a real problem: Matsuzawa does not reveal how many hours of practice either group of subjects have had, but presumably, the humans have not had any practice, while it is explicitly noted that the chimps have had some. The mother-offspring pairs practiced the numerals task from offspring age 4, and then the block task from offspring age 5. Even if we ignore the sample size problems and take the reported results at face value, we are still left with a situation where the mother chimp Ai underperformed the humans, who in turn underperformed the offspring chimp Ayumu--also suggestive of a training effect.

This strikes me as a problem for Matsuzawa's claim, because we know that the ultimate limit of task-specific human memory span is very high compared to a task-general baseline. For instance, Ericsson, Chase and Faloon (1980) reported a case study of a subject who increased their memory span from 7 to 79 in 230 hours of practice, and one need look no further than the world memory records to see that the lack of control for practice seriously undermines Matsuzawa's claim about this unexpected "relationship" between chimp and human WMC.

A more restrained interpretation of the evidence presented in the article would suggest that sufficiently well-trained chimps can outperform untrained humans on the particular task. Any conjecturing about "evolutionary trade-offs" on the basis of these findings seem unwarranted to me, but that would have been the case even if these results had been ironclad.


  • Ericsson, K. A., Chase, W. G., & Faloon, S. (1980). Acquisition of a memory skill. Science, 208(4448), 1181–1182. doi:10.1126/science.7375930
  • Inoue, S., & Matsuzawa, T. (2007). Working memory of numerals in chimpanzees. Current Biology, 17(23), R1004-R1005.
  • 1
    $\begingroup$ +1 for being quicker with the answer I wanted to give ;-) It can be added that during a phase when their brains were in development these chimpanzees were trained over more than one year at ONLY ONE TASK, while a human child learns a multitude of skills in the same time span. If you took a human child and taught it nothing but 1 to 9 for a year, it would probably be equally good at these numbers ... $\endgroup$
    – user1196
    Mar 28, 2013 at 17:46

High working memory is associated with greater ability to learn meanings of abstract symbols, such as is required to do mathematics. I would be highly skeptical of a claim that there is a trade-off between WM and general intelligence.

Ian M. Lyons, Sian L. Beilock, Beyond quantity: Individual differences in working memory and the ordinal understanding of numerical symbols, Cognition, Volume 113, Issue 2, November 2009, Pages 189-204, ISSN 0010-0277, 10.1016/j.cognition.2009.08.003.

Under some circumstances, high WM seems to be associated with poor problem solving under pressure, but not with poor problem solving in general.

From poor performance to success under stress: Working memory, strategy selection, and mathematical problem solving under pressure. Beilock, Sian L.; DeCaro, Marci S. Journal of Experimental Psychology: Learning, Memory, and Cognition, Vol 33(6), Nov 2007, 983-998. doi: 10.1037/0278-7393.33.6.983


It looks like there is a developmental relationship between WM and general IQ:

Fry, A. F., & Hale, S. (1996). Processing speed, working memory, and fluid intelligence: Evidence for a developmental cascade. Psychological science, 7(4), 237-241.

Cole, M. W., Yarkoni, T., Repovš, G., Anticevic, A., & Braver, T. S. (2012). Global Connectivity of Prefrontal Cortex Predicts Cognitive Control and Intelligence. The Journal of Neuroscience, 32(26), 8988-8999.


The answer hinges on the definition of working memory. If we look at synthetics (people with synesthesia who have impressive massive visual memory correlations to time, numbers, etc) definitely not. They are worse in mathematics and stimulation will trigger unrelated memories. Synthetics with obsessive compulsive disorder that obsess about their personal memories are constantly cataloging everything they do.

On the other hand, the information-processing models by which we define intelligence hinge on the information storage capacities of working memory. Sufferers of ADHD show a 10 point drop in IQ because they are unable to persist towards more abstract goals, like learning multiplication tables, and get distracted. This is also what happens in older adults and women hitting menopause (Barkely, Adult ADHD).

  • $\begingroup$ What is OCD? and OTOH...? $\endgroup$
    – draks ...
    Jun 22, 2015 at 22:28

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