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The Interplay Between Input and Initial Biases: Asymmetries in Vowel Perception During the First Year of Life


  • This research was supported by grants from the Spanish Ministerio de Ciencia e Innovación (AP2005-3561, PSI2009-09066, PSI2010-20294, and CONSOLIDER-INGENIO 2010 Programme CDS-2007-00012), and from the Catalan government (SGR 2009-1521). Núria Sebastián-Gallés received the “ICREA Acadèmia” prize for research excellence, funded by the Catalan Government. We are indebted to Xavier Mayoral for his technical support and to Helena Ràfols and Sara Sáez for recruiting the infants for this study. We thank Christopher Fennell, Juan M. Toro and Kimberly A. Brink for comments on earlier drafts of this paper. Special thanks to all the parents and infants who participated in this research.

concerning this article should be addressed to Ferran Pons, Departament de Psicologia Bàsica, Facultat de Psicologia, Universitat de Barcelona, Pg. de la Vall d’Hebron, 171, 08035, Barcelona, Spain. Electronic mail may be sent to


Vowels with extreme articulatory-acoustic properties act as natural referents. Infant perceptual asymmetries point to an underlying bias favoring these referent vowels. However, as language experience is gathered, distributional frequency of speech sounds could modify this initial bias. The perception of the /i/–/e/ contrast was explored in 144 Catalan- and Spanish-learning infants (2 languages with a different distribution of vowel frequency of occurrence) at 4, 6, and 12 months. The results confirmed an acoustic bias at 4 and 6 months in all infants. However, at 12 months, discrimination was not affected by the acoustic bias but by the frequency of occurrence of the vowel.