Sensorimotor adaptation to a nonuniform formant perturbation generalizes to untrained vowels.

When speakers learn to change the way they produce a speech sound, how much does that learning generalize to other speech sounds? Past studies of speech sensorimotor learning have typically tested the generalization of a single transformation learned in a single context. Here, we investigate the ability of the speech motor system to generalize learning when multiple opposing sensorimotor transformations are learned in separate regions of the vowel space. We find that speakers adapt to a nonuniform "centralization" perturbation, learning to produce vowels with greater acoustic contrast, and that this adaptation generalizes to untrained vowels, which pattern like neighboring trained vowels and show increased contrast of a similar magnitude. We show that sensorimotor adaptation of vowels at the edges of the articulatory working space generalizes to intermediate vowels through local transfer of learning from adjacent vowels. These results extend findings on the locality of sensorimotor learning from upper limb control to speech, a complex task with an opaque and nonlinear transformation between motor actions and sensory consequences. Our results also suggest that our paradigm has potential to drive behaviorally relevant changes that improve communication effectiveness.