The Impact of Action Intention Versus Action-Effect Intention on Auditory Prediction Error Signals.

The human brain anticipates the sensory consequences of an action and generates a prediction error (PE) signal when the intended action effect does not occur. This study investigated auditory event-related potential PE markers based on whether participants intended to perform a specific action or produce a specific action effect. Participants were instructed to press a left or right button to produce low- or high-pitched tones, following a visual pattern. The instructions, actions and tone sequences were identical for all participants. The visual patterns differed in two groups: In the action-effect intention group, the visual pattern consisted of 'notes' (indicating low/high pitch). In the action intention group, the visual pattern consisted of 'letters' (indicating left/right button-press). In both groups, a button-press occasionally failed to produce the associated tone (incongruent sounds). The key finding was that these incongruent sounds elicited an enhanced auditory N1 component compared to congruent sounds only in the 'notes' group. We propose that participants in the 'notes' group selected their actions based on the intended action effect, which induced a predictive sensory representation of the expected tone. A violation of this prediction resulted in the early PE, reflected in the auditory N1. Later PE responses, specifically the N2b and P3 components, were observed in both groups. This suggests that action-effect associations were represented, and their violation was processed at a conceptual level even in the 'letters' group. These results support theories postulating that event representations integrate features of stimuli, actions and their associated outcomes.