Can chimpanzees (Pan troglodytes) discriminate appearance from reality?

Journal Article (Journal Article)

A milestone in human development is coming to recognize that how something looks is not necessarily how it is. We tested appearance-reality understanding in chimpanzees (Pan troglodytes) with a task requiring them to choose between a small grape and a big grape. The apparent relative size of the grapes was reversed using magnifying and minimizing lenses so that the truly bigger grape appeared to be the smaller one. Our Lens test involved a basic component adapted from standard procedures for children, as well as several components designed to rule out alternative explanations. There were large individual differences in performance, with some chimpanzees' responses suggesting they appreciated the appearance-reality distinction. In contrast, all chimpanzees failed a Reverse Contingency control test, indicating that those who passed the Lens test did not do so by learning a simple reverse contingency rule. Four-year-old children given an adapted version of the Lens test failed it while 4.5-year-olds passed. Our study constitutes the first direct investigation of appearance-reality understanding in chimpanzees and the first cross-species comparison of this capacity.

Full Text

Duke Authors

Cited Authors

  • Krachun, C; Call, J; Tomasello, M

Published Date

  • September 2009

Published In

Volume / Issue

  • 112 / 3

Start / End Page

  • 435 - 450

PubMed ID

  • 19631933

Electronic International Standard Serial Number (EISSN)

  • 1873-7838

International Standard Serial Number (ISSN)

  • 0010-0277

Digital Object Identifier (DOI)

  • 10.1016/j.cognition.2009.06.012


  • eng