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Ordering of the numerosities 1 to 9 by monkeys
1Department of Psychology, Columbia University, New York, NY 10027, USA. liz@psych.columbia.edu
Science (New York, N.Y.)
|October 23, 1998
Summary
Rhesus monkeys demonstrate an understanding of numerical order, representing numerosities from 1 to 9 on an ordinal scale. This study reveals their capacity for numerical cognition and ordinal disparity detection.
Area of Science:
- Cognitive Science
- Animal Behavior
- Neuroscience
Background:
- A key question in cognitive science is whether animals can represent and computationally use numerical information.
- Numerosity refers to the quantity of elements within a stimulus.
Purpose of the Study:
- To investigate if rhesus monkeys can represent and order visual stimuli based on numerosity.
- To determine if rhesus monkeys can detect ordinal disparity in numerical sequences.
Main Methods:
- Two rhesus monkeys were trained to recognize numerosities 1-4 in ascending order.
- Stimulus exemplars were varied in size, shape, and color to control for non-numerical cues.
- Monkeys were tested on novel numerosities 5-9 without reward to assess their ordering ability.
Main Results:
- Both monkeys successfully ordered novel numerosities (5-9) in an ascending sequence.
- The monkeys demonstrated the ability to generalize their understanding of numerical order to untrained quantities.
- Performance indicated control for non-numerical features of the stimuli.
Conclusions:
- Rhesus monkeys represent numerosities on an ordinal scale from 1 to 9.
- These findings support the presence of numerical representation and ordinal cognition in non-human primates.
- The study provides evidence for sophisticated numerical processing in rhesus monkeys.
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