Monkeys match and tally quantities across senses

Kerry E. Jordan, Evan L. MacLean, Elizabeth M. Brannon

Research output: Contribution to journalArticlepeer-review

74 Scopus citations


We report here that monkeys can actively match the number of sounds they hear to the number of shapes they see and present the first evidence that monkeys sum over sounds and sights. In Experiment 1, two monkeys were trained to choose a simultaneous array of 1-9 squares that numerically matched a sample sequence of shapes or sounds. Monkeys numerically matched across (audio-visual) and within (visual-visual) modalities with equal accuracy and transferred to novel numerical values. In Experiment 2, monkeys presented with sample sequences of randomly ordered shapes or tones were able to choose an array of 2-9 squares that was the numerical sum of the shapes and sounds in the sample sequence. In both experiments, accuracy and reaction time depended on the ratio between the correct numerical match and incorrect choice. These findings suggest monkeys and humans share an abstract numerical code that can be divorced from the modality in which stimuli are first experienced.

Original languageEnglish (US)
Pages (from-to)617-625
Number of pages9
Issue number3
StatePublished - Sep 2008
Externally publishedYes


  • comparative cognition
  • multisensory processes
  • non-human primate
  • number

ASJC Scopus subject areas

  • Language and Linguistics
  • Experimental and Cognitive Psychology
  • Developmental and Educational Psychology
  • Linguistics and Language
  • Cognitive Neuroscience


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