Relative quantity judgments in South American sea lions (Otaria flavescens)

Jose Z. Abramson*, Victoria Hernandez-Lloreda, Josep Call, Fernando Colmenares

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

There is accumulating evidence that a variety of species possess quantitative abilities although their cognitive substrate is still unclear. This study is the first to investigate whether sea lions (Otaria flavescens), in the absence of training, are able to assess and select the larger of two sets of quantities. In Experiment 1, the two sets of quantities were presented simultaneously as whole sets, that is, the subjects could compare them directly. In Experiment 2, the two sets of quantities were presented item-by-item, and the totality of items was never visually available at the time of choice. For each type of presentation, we analysed the effect of the ratio between quantities, the difference between quantities and the total number of items presented. The results showed that (1) sea lions can make relative quantity judgments successfully and (2) there is a predominant influence of the ratio between quantities on the subjects' performance. The latter supports the idea that an analogue representational mechanism is responsible for sea lions' relative quantities judgments. These findings are consistent with previous reports of relative quantities judgments in other species such as monkeys and apes and suggest that sea lions might share a similar mechanism to compare and represent quantities.

Original languageEnglish
Pages (from-to)695-706
Number of pages12
JournalAnimal Cognition
Volume14
Issue number5
DOIs
Publication statusPublished - Sept 2011

Keywords

  • Numerical cognition
  • Relative quantity judgment
  • Sea lion
  • Comparative cognition
  • Accumulator model
  • CHIMPANZEES PAN-TROGLODYTES
  • ORANGUTANS PONGO-PYGMAEUS
  • ZALOPHUS-CALIFORNIANUS
  • DISCRETE QUANTITY
  • MACACA-MULATTA
  • RHESUS-MONKEYS
  • SETS
  • REPRESENTATION
  • EVOLUTION
  • SUMMATION

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