Send to

Choose Destination
J Comp Psychol. 2004 Mar;118(1):25-36.

Chimpanzees (Pan troglodytes) respond to nonvisible sets after one-by-one addition and removal of items.

Author information

Language Research Center, Georgia State University, Decatur, GA, USA.


Two chimpanzees (Pan troglodytes) made numerousness judgments of nonvisible sets of items. In Experiment 1, 1-10 items were dropped 1 at a time into an opaque cup, and then an additional 1-10 items were dropped 1 at a time into another opaque cup. The chimpanzees' performance levels were high and were more dependent on factors indicative of an analogue-magnitude mechanism for representation of set size than on an object file mechanism. In Experiment 2, a 3rd visible set was made available after the sequential presentation of the first 2 sets. The chimpanzees again performed at high levels in selecting the largest of the 3 sets. In Experiment 3, 1 of the 2 initially presented sets was reduced in number by the sequential removal of 1, 2, or 3 items. Both chimpanzees performed above chance levels for the removal of 1, but not more than 1, item.

[Indexed for MEDLINE]

Supplemental Content

Full text links

Icon for American Psychological Association
Loading ...
Support Center