Consequences matter: Self-induced tones are used as feedback to optimize tone-eliciting actions.

Experimental paradigms investigating the processing of self-induced stimuli are often based on the implicit assumption that motor processes are invariable regardless of their consequences: It is presumed that actions with different sets of predictable sensory consequences do not differ in their physical characteristics or in their brain signal reflections. The present experiment explored this assumption in the context of action-related auditory attenuation by comparing actions (pinches) with and without auditory consequences. The results show that motor processes are not invariable: Pinches eliciting a tone were softer than pinches without auditory effects. This indicates that self-induced auditory stimuli are not perceived as irrelevant side effects: The tones are used as feedback to optimize the tone-eliciting actions. The comparison of ERPs related to actions with different physical parameters (strong and soft pinches) revealed a significant ERP difference in the time range of the action-related N1 attenuation (strong pinches resulted in more negative amplitudes), suggesting that a motor correction bias may contribute to this auditory ERP attenuation effect, which is usually attributed to action-related predictive processes.