All Great Ape Species (Gorilla gorilla, Pan paniscus, Pan troglodytes, Pongo abelii) and Two-and- a- Half-Year-Old Children (Homo sapiens) Discriminate Appearance From Reality

Katja Karg*, Martin Schmelz, Josep Call, Michael Tomasello

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)

Abstract

Nonhuman great apes and human children were tested for an understanding that appearance does not always correspond to reality. Subjects were 29 great apes (bonobos [Pan paniscus], chimpanzees [Pan troglodytes], gorillas [Gorilla gorilla], and orangutans [Pongo abelii]) and 24 21/2-year-old children. In our task, we occluded portions of 1 large and 1 small food stick such that the size relations seemed reversed. Subjects could then choose which one they wanted. There was 1 control condition and 2 experimental conditions (administered within subjects). In the control condition subjects saw only the apparent stick sizes, whereas in the 2 experimental conditions they saw the true stick sizes as well (the difference between them being what the subjects saw first: the apparent or the real stick sizes). All great ape species and children successfully identified the bigger stick, despite its smaller appearance, in the experimental conditions, but not in the control. We discuss these results in relation to the understanding of object permanence and conservation, and exclude reversed reward contingency learning as an explanation.

Original languageEnglish
Pages (from-to)431-439
Number of pages9
JournalJournal of Comparative Psychology
Volume128
Issue number4
DOIs
Publication statusPublished - Nov 2014

Keywords

  • appearance-reality
  • Piagetian conservation
  • perspective taking
  • size discrimination
  • quantity estimation
  • YOUNG CHILDREN
  • CONTINGENCY TASK
  • CONSERVATION
  • CHIMPANZEES
  • QUANTITY
  • DISTINCTION
  • KNOWLEDGE
  • PYGMAEUS
  • PSYCHOLOGY
  • JUDGMENTS

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