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Abstract:
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.
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