Perceptual Narrowing of Linguistic Sign Occurs in the 1st Year of Life


  • We thank the infant participants and their parents. We are grateful to Krista Byers-Heinlein and Ramesh Thiruvengadaswamy for indispensable design help and statistical analysis discussions. Funding was provided by the McDonnell Foundation (412783-001G) to Richard N. Aslin and Janet F. Werker; by the National Sciences and Engineering Research Council of Canada (81103) to Janet F. Werker; and by the National Science Foundation (0642632) to Roberta Michnick Golinkoff.

concerning this article should be addressed to Janet F. Werker, Department of Psychology, University of British Columbia, 2136 West Mall, Vancouver, BC V6T1Z4, Canada. Electronic mail may be sent to


Over their 1st year of life, infants’“universal” perception of the sounds of language narrows to encompass only those contrasts made in their native language (J. F. Werker & R. C. Tees, 1984). This research tested 40 infants in an eyetracking paradigm and showed that this pattern also holds for infants exposed to seen language—American Sign Language (ASL). Four-month-old, English-only, hearing infants discriminated an ASL handshape distinction, while 14-month-old hearing infants did not. Fourteen-month-old ASL-learning infants, however, did discriminate the handshape distinction, suggesting that, as in heard language, exposure to seen language is required for maintenance of visual language discrimination. Perceptual narrowing appears to be a ubiquitous learning mechanism that contributes to language acquisition.