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Numerical memory span in a chimpanzee


A female chimpanzee called Ai has learned to use Arabic numerals to represent numbers1. She can count from zero to nine items, which she demonstrates by touching the appropriate number on a touch-sensitive monitor2,3, and she can order the numbers from zero to nine in sequence4,5,6. Here we investigate Ai's memory span by testing her skill in these numerical tasks, and find that she can remember the correct sequence of any five numbers selected from the range zero to nine.

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Figure 1: The chimpanzee Ai performing the five-number ordering task in the ‘masking’ trial.


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Correspondence to Tetsuro Matsuzawa.

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Kawai, N., Matsuzawa, T. Numerical memory span in a chimpanzee. Nature 403, 39–40 (2000).

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