Running Head: Acetaminophen and Evaluation 1 Over-the-Counter Relief from Pains and Pleasures Alike: Acetaminophen Blunts Sensitivity to Both Negative and Positive Reactions

Acetaminophen, an effective and popular over-the-counter pain reliever (e.g., Tylenol®), has recently been shown to blunt individuals’ reactivity to a range of negative stimuli beyond physical pain. Because past psychological and neuroimaging research has linked reduced sensitivity to negative reactions to similarly diminished sensitivity to positive reactions, we conducted two experiments testing whether acetaminophen might blunt individuals’ evaluations and emotional experiences to both negative and positive stimuli alike. In each study, participants received either acetaminophen or placebo, and evaluated emotionally evocative stimuli on valence (Study 1 and 2), emotional arousal (Study 1 and 2), and non-evaluative aspects (Study 2). Results revealed that participants taking acetaminophen (versus placebo) evaluated unpleasant stimuli less negatively and pleasant stimuli less positively, and were less emotionally aroused overall. Conversely, non-evaluative judgments were unaffected by treatment. These findings suggest that the mechanism by which acetaminophen reduces pain may more broadly blunt individuals’ evaluative and emotional processing.