Relative numerousness judgment and summation in young, middle-aged, and older adult orangutans (Pongo pygmaeus abelii and Pongo pygmaeus pygmaeus). |
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Authors: | Anderson, Ursula S. Stoinski, Tara S. Bloomsmith, Mollie A. Maple, Terry L. |
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Abstract: | The ability to select the larger of two quantities ranging from 1 to 5 (relative numerousness judgment [RNJ[) and the ability to select the larger of two pairs of quantities with each pair ranging from 1 to 8 (summation) were evaluated in young, middle-aged, and older adult orangutans (7 Pongo pygmaeus abelii and 2 Pongo pygmaeus pygmaeus). Summation accuracy and RNJ were similar to those of previous reports in apes; however, the pattern of age-related differences with regard to these tasks was different from that previously reported in gorillas. Older orangutans were less accurate than the young and middle-aged for RNJ, and summation accuracy was equivalent among age groups. Evidence was found to suggest that the young and middle-aged based their selection of the largest quantity pair on both quantities within each pair during the summation task. These results show a relationship between subject age and the quantitative abilities of adult orangutans. (PsycINFO Database Record (c) 2010 APA, all rights reserved) |
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Keywords: | quantitative judgment ordinality age differences cognition summation accuracy relative numerousness judgment orangutans |
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