Independent or dependent feature evaluation: A question of stimulus characteristics

Read my lips: Visual speech influences word processing in infants

What do infants hear when they read lips? In the present study, twelve-to-thirteen-month-old infants viewed a talking face produce familiar and unfamiliar words. The familiar words were of three types: in Experiment 1, they were produced correctly (e.g., "bottle"); in Experiment 2, infants saw and heard mispronunciations in which the altered phoneme either visually resembled the original phoneme (visually consistent, e.g. "pottle"), or did not visually resemble the original phoneme (visually inconsistent, e.g., "dottle"). Infants in the correct and consistent conditions differentiated the familiar and unfamiliar words, but infants in the inconsistent condition did not. Experiment 3 confirms that infants were sensitive to the mispronunciations in the consistent condition with auditory-only words. Thus, although infants recognized the consistent mispronunciations when they saw a face articulating the words, they did not with the auditory information alone. These results provide the first evidence that visual articulatory information affects word processing in infants.

Lexical Influences in Audiovisual Speech Perception

Phoneme identification with audiovisually discrepant stimuli is influenced hy information in the visual signal (the McGurk effect). Additionally, lexical status affects identification of auditorily presented phonemes. The present study tested for lexical influences on the McGurk effect. Participants identified phonemes in audiovisually discrepant stimuli in which lexical status of the auditory component and of a visually influenced percept was independently varied. Visually influenced (McGurk) responses were more frequent when they formed a word and when the auditory signal was a nonword (Experiment 1). Lexical effects were larger for slow than for fast responses (Experiment 2), as with auditory speech, and were replicated with stimuli matched on physical properties (Experiment 3). These results are consistent with models in which lexical processing of speech is modality independent.