GENERAL COMMENTARYpublished: 07 July 2015doi: 10.3389/fpsyg.2015.00941Frontiers in Psychology | www.frontiersin.org 1 July 2015 | Volume 6 | Article 941Edited by:Janet F. Werker,The University of British Columbia,CanadaReviewed by:Ruth Tincoff,Bucknell University, USA*Correspondence:Linda Polka,linda.polka@mcgill.caSpecialty section:This article was submitted toLanguage Sciences,a section of the journalFrontiers in PsychologyReceived: 18 May 2015Accepted: 22 June 2015Published: 07 July 2015Citation:Polka L, Bohn O-S and Weiss DJ(2015) Commentary: Revisiting vocalperception in non-human animals: areview of vowel discrimination,speaker voice recognition, andspeaker normalization.Front. Psychol. 6:941.doi: 10.3389/fpsyg.2015.00941Commentary: Revisiting vocalperception in non-human animals: areview of vowel discrimination,speaker voice recognition, andspeaker normalizationLinda Polka 1 *, Ocke-Schwen Bohn 2 and Daniel J. Weiss 31 School of Communication Sciences and Disorders, Centre for Research on Brain, Language, and Music, McGill University,Montreal, QC, Canada,2 Department of English and Center on Autobiographical Memory Research, Department ofPsychology, Aarhus University, Aarhus, Denmark,3 Department of Psychology and Program in Linguistics, The PennsylvaniaState University, University Park, Pennsylvania, PA, USAKeywords: comparative research, vowel perception asymmetries, natural referent vowel framework, infants,non-human animals, task demandsA commentary onRevisiting vocal perception in non-human animals: a review of vowel discrimination, speakervoice recognition, and speaker normalizationby Kriengwatana, B., Escudero, P., and ten Cate, C. (2015) Front. Psychol. 5:1543.doi:10.3389/fpsyg.2014.01543Comparative research provides a unique window into our understanding of human vocalperception. We commend Kriengwatana, Escudero, and ten Cate (KEtC) for providing a much-neededreviewofthisdiverseliterature.Theirappraisalofthreeresearchareashighlightsconceptualand empirical gaps, while also pointing to fruitful directions for future research.Thiscommentaryaddressestheliteratureonasymmetriesinvowelperception.Intheirreviewofthis topic KEtC focus on vowel contrasts that have revealed directional asymmetries in infants andnon-humananimals.Weoffersome clarificationwithrespecttothesestimulusissuesandhighlightanother aspect of this research landscape—the role of task demands—that must also guide futurecomparative investigations.Vowel Perception Asymmetries—Stimulus IssuesThe authors present a detailed overview of studies that reveal directional asymmetries in voweldiscrimination in infants and several non-human species. To date infant perceptual asymmetriescan be accounted for within the NRV framework (Polka and Bohn, 2011). Although directionalasymmetries are evident for vowel pairs tested with cats, vervet monkeys, birds, and macaques,the overall pattern of the asymmetries observed in these species is inconsistent with thepredictions of the NRV model 1 . As KEtC note, contrast-specific comparisons are limited because1 In KEtC’s Figure 1, which plots asymmetries in discrimination of vervets from Sinnott (1989), the arrow going from / v/ to/c/ is in the wrong direction. The asymmetry described with respect to /u/-/ 0 / is also reversed in the first paragraph on pagethree, but correctly displayed in Figure 1.
