Speech Motor Learning Drives Changes in Speech Perception

International audienceRecent work has shown that limb motor learning is accompanied by alterations in perception. For instance, learned compensation for perturbations of reaching movements is associated with changes in the sensed position of the limb (Ostry et al. 2010), changes in evoked potentials from cortical sensory areas (Nasir et al. 2013), and changes in functional connectivity between sensory and motor networks (Vahdat et al. 2011). Motor learning, it seems, involves both changes in motor commands and changes in perception. A recent study showed a similar result in the context of speech (Shiller et al. 2009), and here we test this idea further. In the experiments, speech motor learning was induced by creating a sensorimotor mismatch: an acoustical effects processor was used to alter the sound of the voice in real-time. In one condition subjects repeated "head" but heard themselves producing "had"; in a second condition subjects repeated "head" but heard themselves producing "hid". With training, learned compensation was observed that cancelled out the perceived alteration. Speech perception was assessed before and after speech motor learning using a series of perceptual tests designed to measure the distinction between the words "head", "had", and "hid". Consistent changes in speech perception were observed following learning, but only when speech motor learning drove what subjects produced--not what they perceived themselves producing--into the acoustical range of the perceptual tests. The results show that learned changes in motor commands drive alterations in speech perception following speech production