Don't blame yourself: Conscious source monitoring modulates feedback control during speech production.

Sensory feedback plays an important role in speech motor control. One of the main sources of evidence for this is studies in which online auditory feedback is perturbed during ongoing speech. In motor control, it is therefore crucial to distinguish between sensory feedback and externally generated sensory events. This is called source monitoring. Previous altered feedback studies have taken non-conscious source monitoring for granted, as automatic responses to altered sensory feedback imply that the feedback changes are processed as self-caused. However, the role of source monitoring is unclear. The current study investigated whether conscious source monitoring modulates responses to unexpected pitch changes in auditory feedback. During the first block, some participants spontaneously attributed the pitch shifts to themselves (self-blamers) while others attributed them to an external source (other-blamers). Before Block 2, all participants were informed that the pitch shifts were experimentally induced. The self-blamers then showed a reduction in response magnitude in Block 2 compared with Block 1, while the other-blamers did not. This suggests that conscious source monitoring modulates responses to altered auditory feedback, such that consciously ascribing feedback to oneself leads to larger compensation responses. These results can be accounted for within the dominant comparator framework, where conscious source monitoring could modulate the gain on sensory feedback. Alternatively, the results can be naturally explained from an inferential framework, where conscious knowledge may bias the priors in a Bayesian process to determine the most likely source of a sensory event.