The role of valence in attempted thought suppression.

Thought control was investigated in participants (N = 72) who were shown either a violent, humorous or neutral film and then administered either suppression or nonsuppression instructions. Following the presentation of a three minute segment from one film, participants monitored their thoughts for two 3-minute periods. In Period 1, participants were administered suppression or nonsuppression instructions relating to thoughts of the film. In Period 2, participants were instructed to think about anything. During both periods participants were instructed to press a response button if they had a trauma-related thought. Participants who viewed the violent film gave higher ratings of distress and lower pleasantness ratings than those who viewed the humorous and neutral films. Participants who were given suppression instructions demonstrated a delayed increase in trauma-related thoughts in the period subsequent to suppression across the valence conditions.