The #1 source for news about monkeys and apes

[Amber Hewins <ahewins AT mac.com>]

http://www.sciencedaily.com/releases/2007/12/071203094823.htm   

Young Chimps Top Adult Humans In Numerical Memory

ScienceDaily (Dec. 3, 2007) ? Young chimpanzees have an "extraordinary" 
ability to remember numerals that is superior to that of human adults, 
researchers report.

"There are still many people, including many biologists, who believe that 
humans are superior to chimpanzees in all cognitive functions," said Tetsuro 
Matsuzawa of Kyoto University. "No one can imagine that chimpanzees--young 
chimpanzees at the age of five--have a better performance in a memory task 
than humans. Here we show for the first time that young chimpanzees have an 
extraordinary working memory capability for numerical recollection--better 
than that of human adults tested in the same apparatus, following the same 
procedure."

Chimpanzee memory has been extensively studied, the researchers said. The 
general assumption is that, as with many other cognitive functions, it is 
inferior to that of humans. However, some data have suggested that, in some 
circumstances, chimpanzee memory may indeed be superior to human memory.

In the current study, the researchers tested three pairs of mother and infant 
chimpanzees (all of which had already learned the ascending order of Arabic 
numerals from 1 to 9) against university students in a memory task of 
numerals. One of the mothers, named Ai, was the first chimpanzee who learned 
to use Arabic numerals to label sets of real-life objects with the 
appropriate number.

In the new test, the chimps or humans were briefly presented with various 
numerals from 1 to 9 on a touch-screen monitor. Those numbers were then 
replaced with blank squares, and the test subject had to remember which 
numeral appeared in which location and touch the squares in the appropriate 
order.

The young chimpanzees could grasp many numerals at a glance, with no change 
in performance as the hold duration--the amount of time that the numbers 
remained on the screen--was varied, the researchers found. In general, the 
performance of the three young chimpanzees was better than that of their 
mothers. Likewise, adult humans were slower than all of the three young 
chimpanzees in their response. For human subjects, they showed that the 
percentage of correct trials also declined as a function of the hold 
duration--the shorter the duration became, the worse their accuracy was.

Matsuzawa said the chimps' memory ability is reminiscent of "eidetic 
imagery," a special ability to retain a detailed and accurate image of a 
complex scene or pattern. Such a "photographic memory" is known to be present 
in some normal human children, and then the ability declines with the age, he 
added.

The researchers said they believe that the young chimps' newfound ability to 
top humans in the numerical memory task is "just a part of the very flexible 
intelligence of young chimpanzees."

The researchers include Sana Inoue and Tetsuro Matsuzawa, of Kyoto 
University, Japan. This research was published in the December 4th issue of 
Current Biology, a publication of Cell Press.

Adapted from materials provided by Cell Press.