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Grey parrot numerical competence: a review.

Irene M Pepperberg¹

¹Department of Psychology, Brandeis University, Waltham, MA 02454, USA.

Animal Cognition

|August 16, 2006

Summary

Grey parrots demonstrate advanced numerical abilities, including quantifying sets up to six items and summing quantities. This suggests nonhuman animals can grasp number symbols as abstract concepts.

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Area of Science:

Comparative psychology
Animal cognition
Numerical cognition

Background:

Debate exists on nonhuman numerical competency, with some suggesting only basic quantity understanding (<4).
Training in human communication systems may enhance nonhuman numerical abilities.
Grey parrots (Psittacus erithacus) offer a unique model for studying complex cognitive skills.

Purpose of the Study:

To review evidence of numerical competency in a Grey parrot.
To assess the parrot's understanding of quantity and number symbols.
To compare the parrot's numerical skills to other species and human children.

Main Methods:

Review of existing research data on a specific Grey parrot.
Vocal quantification of item sets (up to six) using English labels.
Assessment of comprehension of numerical labels and a zero-like concept.
Analysis of recent studies on the parrot's ability to sum quantities.

Main Results:

The Grey parrot quantifies sets up to six items, including heterogeneous subsets.
The parrot demonstrates full comprehension of numerical labels.
The parrot possesses a zero-like concept and can sum small quantities.
The parrot's numerical sense is comparable to chimpanzees and young human children.

Conclusions:

Grey parrots can understand number symbols as abstract representations.
This parrot's numerical abilities challenge previous assumptions about nonhuman cognition.
Numerical cognition in nonhumans may be more sophisticated than previously thought.

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