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Shared system for ordering small and large numbers in monkeys and humans
Jessica F Cantlon1, Elizabeth M Brannon
1Department of Psychological, Duke University, Durham, NC 27708, USA. jfc2@duke.edu
Psychological Science
|May 11, 2006
Summary
Rhesus monkeys demonstrate an impressive numerical capacity, extending learned rules to larger numbers without an apparent upper limit. This suggests a shared, evolutionarily primitive mechanism for numerical cognition between monkeys and humans.
Area of Science:
- Comparative psychology
- Cognitive neuroscience
- Animal cognition
Background:
- Growing evidence suggests shared numerical representation systems between humans and animals.
- Understanding the limits and mechanisms of non-human numerical cognition is crucial for evolutionary insights.
Purpose of the Study:
- To investigate the upper numerical limits in rhesus monkeys.
- To compare numerical cognition mechanisms between rhesus monkeys and humans.
Main Methods:
- Rhesus monkeys were trained on a numerical rule with small values and tested on larger, untrained values.
- A direct comparison of ordinal comparison task performance was conducted between humans and monkeys.
Main Results:
- Rhesus monkeys successfully extended numerical rules to values up to 30, indicating no discernible upper limit within the tested range.
- Performance in numerical ordering was consistently influenced by the ratio of values, not absolute magnitude.
- Human and monkey performance showed striking qualitative and quantitative similarities.
Conclusions:
- Rhesus monkeys possess a robust numerical capacity that extends beyond small quantities.
- The findings provide strong evidence for a shared, evolutionarily ancient, non-verbal mechanism for numerical representation and comparison in humans and monkeys.