||Developmental change in infants' detection of visual faces that match auditory vowels
Infants demonstrate robust audiovisual (AV) perception, detecting, for
example, which visual face matches auditory speech in many paradigms. For
simple phonetic segments, like vowels, previous work has assumed developmental
stability in AV matching. This study shows dramatic differences in
matching performance for different vowels across the first year of life: 3-, 6-,
and 9-month-olds were familiarized for 40 sec with a visual face articulating
a vowel in synchrony with auditory presentations of that vowel, but crucially,
the mouth of the face was occluded. At test, infants were shown two
still photos of the same face without occlusion for 1 min in silence. One face
had a static articulatory configuration matching the previously heard vowel,
while the other face had a static configuration matching a different vowel.
Three auditory vowels were used: /a/, /i/, and /u/. Results suggest that AV
matching performance varies according to age and to the familiarized vowel.
Interestingly, results are not linked to the frequency of vowels in auditory
input, but may instead be related to infants’ ability to produce the target vowel. A speculative hypothesis is that vowel production in infancy modulates
AV vowel matching.