Adaptation to Auditory Errors Modulates Perception of the Errors.

Abstract

Purpose: Speakers adapt to auditory feedback perturbations by modifying their speech output. Although formant-clamp perturbations, in which feedback formants are fixed at predetermined values independent of the speaker's production, demonstrate that adaptation relies on the motor-to-auditory correspondence, it remains unclear how speakers perceive this feedback during adaptation. We hypothesized that if motor adaptation influences perception, then perceptual judgments of experience errors would change alongside adaptation, even when auditory feedback is held constant.

Method: Thirty healthy adults performed an adaptation task across four conditions: formant-shift and formant-clamp perturbations, each introduced either suddenly or gradually. During each trial, participants produced consonant-vowel-consonant words and reported their perceived auditory feedback using a continuous vowel-identification slider. We quantified adaptive motor responses during the first 100 ms of the vowel and compared them with perceived errors derived from perceptual reports.

Results: We found that, across all conditions, participants adapted, but formant-shift perturbations elicited significantly greater adaptation and smaller perceived error than formant-clamped feedback. Critically, adaptive responses positively correlated with perceived errors in the suddenly and gradually introduced formant-shift conditions and the suddenly introduced formant-clamp condition, but not in the gradually introduced formant-clamp condition.

Conclusions: These findings provide compelling evidence that perception and speech motor adaptation are tightly linked. However, this relationship is not uniform, and it depends on the nature of the perturbation. This suggests that sensorimotor control of speech relies on context-dependent integration of sensory information, rather than a fixed mapping between perception and action.