Amy Perfors, Kalee Geidermann Magnani & Anne Fernald
Stanford University
amyfrancesca@stanfordalumni.org
Recent studies using on-line measures of spoken language understanding show that infants make remarkable gains in the speed and accuracy of word recognition across the second year of life (1-3). Research to date has focused on group differences reflecting age-related changes in speech processing efficiency rather than on individual differences. How stable are these on-line measures of speech processing over the second year for individual children? And how are these on-line measures of speech processing related to other aspects of language competence? Controlling for age, are children who are relatively faster and more reliable in recognizing spoken words also more advanced in speech production?
To address these questions, we followed 64 infants longitudinally from 12 to 25 months of age. At 15, 18, 21, and 25 months, children were tested in an eye-tracking procedure which enabled measurement of their reaction times and accuracy in spoken word recognition (1). The technique of monitoring children's eye movements as they look at pictures while listening to speech yields precise information about the time course of word recognition in the early stages of language learning. Children were tested on the same familiar words at each age, with increasingly difficult items added at each time point to keep the task challenging. At each age we collected vocabulary data based on maternal report, using the MacArthur CDI. At 25 months, comprehension was also assessed in a picture pointing task based on the Peabody Picture Vocabulary Test (PPVT).
Preliminary analysis reveal that the average speed of word recognition at 25 months is correlated with mean RT at 15 (r = .38) and 18 months (r=.38). Mean RT at 25 months is also correlated with size of the productive vocabulary at every age: at 12 (r = -.36); 15 (r = -.34); 18 (r = -.35); 21 (r = -.43); and 25 months (r = -.36). Moreover, speed and accuracy of on-line word recognition at 25 months are strongly correlated with performance on the PPVT at the same age (PPVT / mean RT, r = -.55; PPVT / mean % correct, r = .57). These findings attest to the stability and the validity of recently developed on-line measures of efficiency in young children's spoken word recognition. Speed and reliability in spoken language comprehension are increasingly stable over the second year, and clearly relate to other convergent measures of developing language competence.
References
(1) Fernald, A., Pinto, J. P., Swingley, D., Weinberg, A., & McRoberts, G. W. (1998). Rapid gains in speed of verbal processing by infants in the second year. Psychological Science, 9: 72-75.
(2) Fernald, A., Swingley, D., & Pinto, J. P. (2001). When half a word is enough: Infants can recognize spoken words using partial phonetic information. Child Development, 72: 1003-1015.
(3) Swingley, D., Pinto, J. P., & Fernald, A. (1999). Continuous processing in word recognition at 24 months. Cognition, 71, 73-108.