Perceptual learning

Previous research has demonstrated that sensitivity to unimodal nonnative speech
contrasts generally narrows during the first year. Although other work has demonstrated
a processing advantage for multimodal stimuli, research on infants' responsiveness to
nonnative contrasts so far has not examined whether concurrent auditory and visual
speech information can modulate perceptual narrowing. Thus, the current study
investigated the influence ofbimodally specified speech sounds on infants' sensitivity to
a nonnative phonemic contrast. Six-month-old and 10- to 12-month-old infants were
tested in a habituation/test procedure for discrimination of an audiovisual nonnative
speech contrast (Hindi /tal dental vs. /Tal retroflex stop). Findings showed that infants at
both ages exhibited evidence of discrimination following habituation to one of the speech
sounds. These findings suggest that the usually observed decline in responsiveness to
nonnative speech contrasts is limited to audibly specified contrasts and that concurrent
visual speech information enhances the discriminability of such contrasts.

This study examines whether forming a single identity is crucial to learning to bind faces and voices, or if people are equally able to do so without tying this information to an identity. To test this, individuals learned paired faces and voices that were in one of three different conditions: True voice, Gender Matched, or Gender Mismatched conditions. Performance was measured in a training phase as well as a test phase, and results show that participants were able to learn more quickly and have higher overall performance for learning in the True Voice and Gender Matched conditions. During the test phase, performance was almost at chance in the Gender Mismatched condition which may mean that learning in the training phase was simply memorization of the pairings for this condition. Results support the hypothesis that learning to bind faces and voices is a process that involves forming a supramodal identity from multisensory learning.