Beyond feedback processing: Approach and avoidance behaviors modulate midline EEG delta and theta signals

Background: : Approach-avoidance motivations guide behavior and involve distinct electrocortical patterns. Feedback processing and outcome monitoring literature shows that delta (1 – 3 Hz) activity relates to reward processing while theta (4 – 7 Hz) activity relates to threat, error, and conflict monitoring. However, these event-related potentials (ERPs) have not been examined during motivational behaviors toward or away from appetitive or aversive stimuli. The current study investigated whether event-related frequency dynamics are sensitive to motivational direction and movements. Methods: : N = 86 participants completed a mobile approach-avoidance task involving pulling and pushing appetitive dessert images and aversive disgusting images while EEG was recorded. We used the binomial reduced interference distribution (RID) to extract delta and theta power, then compared time domain ERPs to evoked frequency dynamics. Results: : ERP analysis and repeated measures ANOVA showed N2 amplitude varied by image type, and P3 by both image type and task movement direction, without statistical interaction. Time-frequency ERP analysis revealed that differences in delta power were enhanced when pulling dessert images and attenuated when pushing dessert images. Theta differences 156 – 312ms post-stimulus were enhanced to aversive images, regardless of behavior. Sustained theta differences 500 – 1000ms post-stimulus showed relative enhancement when pulling disgusting images compared to pushing disgusting images. Conclusions: : RID time-frequency delta and theta power dynamics appear to reflect active monitoring processes during approach and avoidance behaviors. Results suggest that approach motivation enhances delta activity while avoidance motivation enhances theta activity. Importantly, theta enhancement manifested as a longer signal duration during motivational conflict. These results demonstrate the sensitivity of time-frequency ERP components to affective motivation and movement direction.