Mathematical Chimpanzees

Tue, 22 Aug 1995 17:16:17 CDT

I posted a query recently about research on the mathematical
abilities of chimpanzees. To my surprise, nobody was able to help; I
had to go find it myself! In a remarkable series of experiments, the
researchers let a chimp select a larger or smaller amount of candy (2-6
pieces). The catch was that if the chimp picked the larger amount, the
candy itself would be given to an observer-chimp instead of the
selector; the selector would get the smaller amount. Remarkably, the
chimps couldn't seem to get the hang of it as long as they were
confronted with the candy; but when Arabic numerals were substituted,
they quickly learned to get the larger amount for themselves by picking
the lower number. Conclude the researchers: "These findings suggest
that a basic predisposition to respond to the perceptual motivational
features of incentive stimuli can interfere with task performance and
that this interference can be overridden when abstract symbols serve as
choice stimuli." The reference is: Boysen, Sarah T. & Bernston, Gary G.
(Ohio State University Department of Psychology, Comparative Cognition
Project, Columbus). "Responses to Quantity: Perceptual versus Cognitive
Mechanisms in Chimpanzees (*Pan troglodytes)," Journal of Experimental
Psychology: Animal Behavior Processes 21 (Jan., 1995):82-86.
--Bob Graber