Effects of seeing and hearing speech on speech production: a response time study.

Research demonstrates that listening to and viewing speech excites tongue and lip motor areas involved in speech production. This perceptual-motor relationship was investigated behaviourally by presenting video clips of a speaker producing vowel-consonant-vowel syllables in three conditions: visual-only, audio-only, and audiovisual. Participants identified target letters that were flashed over the mouth during the video, either manually or verbally as quickly as possible. Verbal responses were fastest when the target matched the speech stimuli in all modality conditions, yet optimal facilitation was observed when participants were presented with visual-only stimuli. Critically, no such facilitation occurred when participants were asked to identify the target manually. Our findings support previous research suggesting a close relationship between speech perception and production by demonstrating that viewing speech can 'prime' our motor system for subsequent speech production.