Ayumu the Chimpanzee, Incredible Memory, and Skepticism

One of my Facebook friends recently posted an article about Ayumu the chimpanzee, who is world renowned for his memory feats in the laboratory setting. If you watch the video of what Ayumu can do in the laboratory, it seems absolutely incredible and is no doubt impressive. You can see a good demonstration that is well worth watching below of what Ayumu can do.



As impressive as this video is, I could have sworn I remembered some controversy over this after seeing this several years ago. So I went to PubMed, which is the best online repository for peer-reviewed research articles and I found the following.

Silberberg A, Kearns D. Anim Cogn. 2009 Mar;12(2):405-7. Epub 2008 Dec 30.  

Memory for the order of briefly presented numerals in humans as a function of practice.

Inoue and Matsuzawa (Curr Biol 17: R1004-R1005, 2007) showed that with an accuracy of approximately 79%, the juvenile chimpanzee Ayumu, could recall the position and order of a random subset of five Arabic numerals between one and nine when those numerals were presented for only 210 ms on a computer touch screen before being masked with white squares. None of nine humans working on the same task approached this level of accuracy. Inoue and Matsuzawa (2007) claimed this performance difference was evidence of a memorial capacity in young chimpanzees that was superior to that seen in adult humans. While the between-species performance difference they report is apparent in their data, so too is a large difference in practice on their task: Ayumu had many sessions of practice on their task before terminal performances were measured; their human subjects had none. The present report shows that when two humans are given practice in the Inoue and Matsuzawa (2007) memory task, their accuracy levels match those of Ayumu.

Moral of the story: When sometimes seems very out of the ordinary, approach with a degree of skepticism. Nevertheless, I'm still very impressed with Ayumu!