Wednesday, December 05, 2007

Chimps Beat Humans, But How?

The performance of these chimpanzees is very impressive. It highlights another cognitive capacity that these animals exhibit and supports the idea of their high intelligence. Studies such as this one are useful for demonstrating similarities and differences in human and nonhuman animal abilities through direct comparison.

I do wonder whether this advantage of chimpanzees over humans really is less about retention and recollection of information in working memory and more the result of differences in processing speed of stimuli. These things are related, of course, but there is evidence that some nonhuman primates enjoy an advantage over humans in terms of their processing speed of certain kinds of stimuli and their speed in responding. In this paper, human performance suffered in comparison to one young chimpanzee in exactly the condition where the presentation of the numbers was so short that humans may not have been able to process all of them. This suggests that the chimpanzee processed the numbers faster than the humans did. If true, we need
to understand what the benefits and costs are for such fast processing (and why processing speed may change across the lifespan, as the older chimpanzee did not perform as well as either the young chimpanzee or the humans). Understanding how humans might have benefited from the substitution of other cognitive skills in place of pure processing speed may highlight an important component in the evolution of human cognition.

I also wonder about the effects of experience. The chimpanzees were highly experienced with the task (one might even claim that they reached a level of expertise in terms of their training), and I suspect humans who had an equal amount of practice might improve their performance. Extensive practice or experience often changes perceptual and cognitive abilities (think of the musician who can detect the slightest note out of tune where the non-musician cannot), and this can happen in situations requiring rapid processing of stimuli (as with the chess master who surveys a board only briefly and knows instantly who has the upper hand).

So, it remains to be seen whether this is really an advantage of chimpanzee memory over human memory or the result of some other effect such as amount of practice or speed of processing (or perhaps it is some combination of all of these). It may be that chimpanzees do have a true memory advantage, and the researchers have suggested an interesting and viable hypothesis for why this might be the case. Questions remain, but they certainly do not diminish the impressive performance shown by these chimpanzees or the importance of these data for our understanding of the evolution of cognition.

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