Spontaneous Use of Magnitude Discrimination andOrdination by the Orangutan (Pongo pygmaeus)
Publication Type: |
Journal Article |
Year of Publication: |
2001 |
Authors: |
R.W. Shumaker, A.M. Palkovich, B.B. Beck, G.A. Guagnano, H. Morowitz |
Publication/Journal: |
Journal of Comparative Psychology |
Keywords: |
animals, appetitive behavior, attention, discrimination learning, female, male, motivation, pongo pygmaeus/psychology, problem solving |
Abstract:
The ability to discriminate quantity is descriptive of general cognitive ability. In this study, the authors presented 2 orangutans (Pongo pygmaeus) with a quantity judgment task. Each trial consisted of 2 choices, ranging from 1 to 6 food items in each. The orangutan chose 1 of the quantities, which was removed, and the remaining array was given as a reward. In contrast to chimpanzees previously tested on the same task (S. T. Boysen & G. G. Berntson, 1995; S. T. Boysen, G. G. Berntson, M. B. Hannan, & J. T. Cacioppo, 1996; S. T. Boysen, K. L. Mukobi, & G. G. Berntson, 1999), the orangutans optimized their performance. Orangutans, therefore, attend to differences in magnitude and can spontaneously use ordinality. Results also suggest a cognitive difference between chimpanzees and orangutans.