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Comparative and categorical spatial judgments in the monkey: "high" and "low".
Antonio F Fortes1, Hugo Merchant, Apostolos P Georgopoulos
1Brain Sciences Center, Veterans Affairs Medical Center, One Veterans Drive, Minneapolis, MN 55417, USA.
Animal Cognition
|April 8, 2004
Summary
Rhesus monkeys can form abstract concepts of "high" and "low" categories, similar to humans. The study also observed the congruity effect in monkeys, suggesting analogical processing in spatial categorization.
Area of Science:
- Cognitive psychology
- Comparative cognition
- Primate behavior
Background:
- Humans use an abstract midline to categorize object height into "high" or "low".
- Children lack this abstract midline concept and directional understanding of height categories.
- The congruity effect, a decrease in response time near category poles, is observed in humans.
Purpose of the Study:
- To investigate if rhesus monkeys can perform categorical judgments of spatial height.
- To determine if the congruity effect is present in rhesus monkeys.
- To inform competing hypotheses (analog vs. semantic models) explaining the congruity effect in humans.
Main Methods:
- A rhesus monkey was trained using delayed match-to-sample tasks.
- The monkey had to categorize objects into "high" or "low" height categories.
- Response times were analyzed to identify the presence of the congruity effect.
Main Results:
- The rhesus monkey successfully generated an abstract midline concept for height categorization.
- The congruity effect was observed in the monkey's performance.
- The monkey's categorization abilities were comparable to adult humans.
Conclusions:
- Rhesus monkeys demonstrate abstract spatial categorization abilities, including the formation of a midline concept.
- The presence of the congruity effect in monkeys supports an analog comparison model for spatial judgment.
- These findings suggest non-propositional cognitive mechanisms underlie spatial categorization in primates.