Using computer-mediated joystick manipulation, the ability of a common chimpanzee (Pan troglodytes) to select arrays of items equal to a given target number was examined. A random dot condition was included in which all sequence cues were eliminated as a means to reach the target numbers 1 to 4. The participant, Austin, had only the quantity of items already selected as a record of how high the count had progressed. Performance on the random dot trials was found to be significantly above chance and improvement over time was also statistically significant. Results of this experiment provide evidence that Austin behaved with a knowledge that the quantity of items selected was the objective of the task rather than adhering rigidly to any specific pattern of selection. The results indicate that Austin had the ability to discriminate the number of items needed to reach the target number and then select items individually to reach that target quantity.
Beran, Michael J.; Rumbaugh, Duane M.; and Savage-Rumbaugh, E. Sue
"Chimpanzee (Pan Troglodytes) Counting in a Computerized Testing Program,"
The Psychological Record: Vol. 48
, Article 1.
Available at: http://opensiuc.lib.siu.edu/tpr/vol48/iss1/1