Rhesus Monkeys (Macaca mulatta) Hear Rising Frequency Sounds as Looming

Asif A. Ghazanfar, Joost X. Maier

Research output: Contribution to journalArticle

13 Scopus citations

Abstract

Rising sound intensity provides an important cue for the detection of looming objects. Studies with humans indirectly suggest that rising pitch can also signal a looming object. This link between rising intensity and rising frequency is puzzling because no physical rise in frequency occurs when a sound source approaches. Putative explanations include (a) the idea that the loudness of sound depends on its frequency, (b) the frequent co-occurrence of rising intensity with rising frequency in vocalizations generates an association between the 2 features, and (c) auditory neurons process amplitude- and frequency-modulated sounds similarly. If these hypotheses are valid, then rhesus monkeys (Macaca mulatta)-which share some homologies in the vocal production apparatus and auditory system-should also associate rising frequency with rising intensity, and thus should perceive rising frequency as a looming sound source. A head-turning assay and a preferential-looking paradigm revealed that monkeys show an attentional bias toward rising versus falling frequency sounds and link the former to visual looming signals. This suggests that monkeys hear a rising frequency sound as a looming sound source even though, in the real world, no such link exists.

Original languageEnglish (US)
Pages (from-to)822-827
Number of pages6
JournalBehavioral Neuroscience
Volume123
Issue number4
DOIs
StatePublished - Aug 1 2009

All Science Journal Classification (ASJC) codes

  • Behavioral Neuroscience

Keywords

  • audiovisual looming
  • doppler effect
  • multisensory
  • time-to-arrival
  • time-to-collision

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