The relevance of visual information on learning sounds in infancy

Newborn infants are sensitive to combinations of visual and auditory speech. Does this ability to match sounds and sights affect how infants learn the sounds of their native language? And are visual articulations the only type of visual information that can influence sound learning? This dissertation focuses on how infants discover phonological categories in their input by using information from both the visual and auditory modalities. By using eye tracking equipment, it was possible to measure infants’ gaze locations during different types of training as well as to assess infants’ discrimination of the vowel contrast after learning. Key findings are that combinations of auditory and visual information can increase infants’ attention during learning; that infants look for visual articulation information when they hear an unfamiliar speech contrast; and that infants’ looking behavior at 8 months when presented with visual objects and speech sounds can predict their vocabulary size 10 months later. From very early on, infants can benefit from the rich auditory and visual environment into which they are born.