My research focuses on describing and understanding the critical first steps in infancy that launch the process of language acquisition. I study infants from birth up to two years of age to reveal the perceptual biases humans have at the beginning of life, and how those are sculpted through maturation, experience, and development to yield the perceptual categories the child uses in language acquisition.

Critical periods
There is continuing debate as to whether speech perception is characterized by critical periods, i.e. windows in development when the perceptual system is most open to experience-based tuning. Recent work suggests that Gamma-aminobutyric acid (GABA: an inhibitory neurotransmitter) circuit maturation triggers the critical period for visual cortical plasticity, as exemplified by premature onset in mice treated with benzodiazepines. Given that GABA triggers visual cortical plasticity in mice, I am now collaborating with T. Hansch at Harvard University, and T. Oberlander and W. Weikum in the Centre for Community Child Health to study speech perception in human infants exposed to benzodiazepines and other drugs during prenatal and early pre- and perinatal development, asking whether exposure to these substances changes the timing of perceptual plasticity for speech sounds, and whether differential timing of the onset of plasticity has the cascading effects on subsequent language development. This work, together with an epigenetic analysis component, was recently funded by the Human Frontiers Science Program (with T. Hensch as PI).

Studying the link between speech perception and language acquisition
In previous work we have shown that although infants have established native language speech sound categories by the end of the first year, and although they can use these categories to show differentiation of well-known words shortly after their first birthday, infants have difficulty using speech sound categories to guide the learning of new words. Recently we have shown that individual differences in infant performance in this task at 18 months of age predict later language development. We are currently following up this work and comparing infants at genetic risk for a language delay (first degree relative with a phonological disability) to typically developing infants on their ability to use native speech sound categories to direct word learning at 17 months, and then following the children longitudinally.

Studying infants growing up bilingual
Babies who grow up with two languages face a different set of challenges in speech perception and word learning than do infants who grow up with only one language. We are currently undertaking a number of studies comparing bilingual and monolingual infants. These include a) tests of whether bilingual newborn infants can discriminate their two languages, or whether they mix both languages together; b) tests of speech sound discrimination in bilingual in comparison to monolingual infants; c) tests of word learning in bilingual infants (do they assume that each object can have only one label as monolingual infants do? Or are they more willing to accept two labels for each object?); and, d) tests of visual speech discrimination in bilingual infants (are they better able to discriminate languages than monolinguals when just watching silent, talking faces?)

Werker, J. F., Byers-Heinlein, K., & Fennell, C. (2009). Bilingual beginnings to learning words. Philosophical Transactions of the Royal Society B: Biological Sciences, 364(1536), 3649-3663.

Yeung, H. H., & Werker, J. F. (2009). Learning words’ sounds before learning how words sound: 9-Month-olds use distinct objects as cues to categorize speech information. Cognition, 113(2), 234-243.

Fais, L., Kajikawa, S., Amano, S., & Werker, J. F. (2009). Infant discrimination of a morphologically relevant word-final contrast. Infancy, 14(4), 488-499.

Byers-Heinlein, K., & Werker, J. F. (2009). Monolingual, bilingual, trilingual: Infants’ language experience influences the development of a word learning constraint. Developmental Science, 12(5), 815-823.

Yoshida, K. A., Fennell, C. T., Swingley, D., & Werker, J. F. (2009). Fourteen month-old infants learn similar sounding words. Developmental Science, 12(3), 412-418.

Mugitani, R., Pons, F., Fais, L., Werker, J. F., & Amano, S. (2009). Perception of vowel length by Japanese- and English-learning infants. Developmental Psychology, 45(1), 236-247.

Werker, J. F., & Byers-Heinlein, K. (2008). Bilingualism in infancy: First steps in perception and comprehension of language. Trends in Cognitive Sciences, 12(4), 144-151.

Dietrich, C., Swingley, D., & Werker, J. F. (2007). Native language governs interpretation of salient speech sound differences at 18 months. Proceedings of the National Academy of Sciences, USA, 104(41), 16027-16031.

Fennell, C. T., Byers-Heinlein, K., & Werker, J. F. (2007). Using speech sounds to guide word learning: The case of bilingual infants. Child Development, 78(5), 1510-1525.

Vouloumanos, A., & Werker, J. F. (2007). Listening to language at birth: Evidence for a bias for speech in neonates. Developmental Science, 10(2), 159-164.

Weikum, W., Vouloumanos, A., Navarro, J., Soto-Faraco, S., Sebastián-Gallés, N., & Werker, J. F. (2007). Visual language discrimination in infancy. Science, 316(5828), 1159.

Werker, J. F., Pons, F., Dietrich, C., Kajikawa, S., Fais, L., & Amano, S. (2007). Infant-directed speech supports phonetic category learning in English and Japanese. Cognition, 103(1), 147-162.

Werker, J. F., & Yeung, H. H. (2005). Infant speech perception bootstraps word learning. Trends in Cognitive Sciences, 9(11), 519-527.

Mills, D. L., Prat, C., Zangl, R., Stager, C. L., Neville, H. J., & Werker, J. F. (2004). Language experience and the organization of brain activity to phonetically similar words: ERP evidence from 14- and 20-month olds. Journal of Cognitive Neuroscience, 16(8), 1-13.

Maye, J., Werker, J. F., & Gerken, L. A. (2002). Infant sensitivity to distributional information can affect phonetic discrimination. Cognition, 82(3), B101-B111.

Fellow, Association for Psychological Science – 2009

Delivered the 10th Annual Maryland-Blackwell Lectures, University of Maryland – 2008

Catholic University of Santiago, Chile, Distinguished Visitor – 2007

Jacob Biely Prize, UBC’s Top Research Award – 2008

Nominated by Psychology Department for UBC Killam Award for Graduate Mentoring – 2006

Elected Fellow, American Association for the Advancement of Science – 2006

Fellow, Canadian Institutes of Advanced Research – 2004-present

Chair (Tier 1), Canada Research Chair Program – 2001-present

Elected, Fellow of the Royal Society of Canada – 2001

Distinguished Visiting Scientist, Max Planck Institute/Psycholinguistics, Nijmegen NL – 2001

Elected Fellow, Canadian Psychological Association – 1996

Killam Research Prize – 1991

Killam Leave Fellowship – 1990-1991

UBC Alumni Prize for Research in the Social Sciences – 1990