Summation and numerousness judgments of sequentially presented sets of items by chimpanzees (Pan troglodytes) | JoVE Visualize

Summation and numerousness judgments of sequentially presented sets of items by chimpanzees (Pan troglodytes)

M J Beran¹

¹Department of Psychology, Georgia State University, Decatur 30034, USA. mjberan@yahoo.com

Journal of Comparative Psychology (Washington, D.C. : 1983)|July 19, 2001

View abstract on PubMed

Summary

Chimpanzees can mentally track and combine quantities even when items are presented sequentially and not fully visible. This demonstrates advanced numerical cognition in primates.

Area of Science:

Cognitive Science
Primatology
Animal Behavior

Background:

Understanding numerical cognition in non-human primates provides insights into the evolution of mathematical abilities.
Investigating how animals process quantities is crucial for comparative psychology.

Purpose of the Study:

To determine if chimpanzees can make numerousness judgments with sequentially presented quantities.
To assess the ability of chimpanzees to mentally combine and compare non-visible sets of items.

Main Methods:

Two chimpanzees (Pan troglodytes) were presented with M&Ms in sequential sets, varying in number and presentation format (single vs. multiple subsets).
Chimpanzees' choices between two quantities were recorded across four experiments, including conditions with hidden items and item removal.
Performance was analyzed for statistical significance against chance levels.

Main Results:

Chimpanzees successfully selected the larger quantity in experiments with simpler sequential presentations (1-9 items, two subsets).
Performance varied in more complex conditions (three subsets, item removal), with one chimpanzee significantly outperforming chance.
Results indicate a capacity for mental representation and combination of quantities.

Conclusions:

Chimpanzees possess the cognitive ability to mentally represent and sum quantities from sequentially presented, non-visible sets.
This study supports the idea that foundational numerical skills are present in non-human primates.
The findings contribute to our understanding of the evolution of quantitative reasoning.