Discrete quantity judgments in the great apes (Pan paniscus, Pan troglodytes, Gorilla gorilla, Pongo pygmaeus): The effect of presenting whole sets versus item-by-item

Daniel Hanus*, Josep Call

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

155 Citations (Scopus)

Abstract

The authors examined quantity-based judgments for up to 10 items for simultaneous and sequential whole sets as well as for sequentially dropped items in chimpanzees (Pan troglodytes), gorillas (Gorilla gorilla), bonobos (Pan paniscus), and orangutans (Pongo pygmaeus). In Experiment 1, subjects had to choose the larger of 2 quantities presented in 2 separate dishes either simultaneously or I dish after the other. Representatives of all species were capable of selecting the larger of 2 quantities in both conditions, even when the quantities were large and the numerical distance between them was small. In Experiment 2, subjects had to select between the same food quantities sequentially dropped into 2 opaque cups so that none of the quantities were ever viewed as a whole. The authors found some evidence (albeit weaker) that subjects were able to select the larger quantity of items. Furthermore, the authors found no performance breakdown with the inclusion of certain quantities. Instead, the ratio between quantities was the best performance predictor. The authors conclude that quantity-based judgments rely on an analogical system, not a discrete object file model or perceptual estimation mechanism, such as subitizing.

Original languageEnglish
Pages (from-to)241-249
Number of pages9
JournalJournal of Comparative Psychology
Volume121
Issue number3
DOIs
Publication statusPublished - Aug 2007

Keywords

  • quantity estimation
  • relative numerousness
  • great apes
  • accumulator model
  • quantitative abilities
  • PIAGETIAN LIQUID CONSERVATION
  • NUMERICAL COMPETENCE
  • ONE ADDITION
  • SUMMATION
  • REPRESENTATIONS
  • INFANTS
  • MONKEYS
  • NUMBER
  • ANALOG
  • FOOD

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