Sequential modulations of valence processing in the emotional Stroop task.

This study investigated trial-to-trial modulations of the processing of irrelevant valence information. Participants (N = 126) responded to the frame color of pictures with positive, neutral, or negative affective content--a procedure known as an emotional Stroop task (EST). As is typically found, positive and negative pictures delayed responses as compared to neutral pictures. However, the type and extent of this valence-based interference depended on the irrelevant picture valence in the preceding trial. Whereas preceding exposure to negative valence prompted interference from positive and negative pictures, such interference was removed after neutral trials. Following positive pictures, interference from negative but not from positive pictures was observed. We suggest that these sequential modulations reflect automatic self-regulatory selection processes that help to keep the balance between attending to task-relevant information and task-irrelevant information that signals important changes in the environment.