Acetaminophen Does Not Alter the Early Processing of Emotional Facial Expressions: An Eye-tracking Study

A growing body of research has uncovered that acetaminophen, the most commonly used over-the-counter painkilling drug in the United States, produces a number of unintended psychological effects. In particular, recent studies show that acetaminophen blunts a variety of adaptive affective and cognitive processes, including our sensitivity to painful social experiences and subjective responses to emotional stimuli. Using a double-blind placebo-controlled study, here we examined whether acetaminophen alters the early visual processing of emotional facial expressions. Participants consumed 1000 mg of acetaminophen, or a matched placebo, prior to performing a delayed disengagement task with different facial expressions. Specifically, we used eye-tracking software to assess the latency to look away from neutral, happy, and angry faces. Based on prior research, we hypothesized that acetaminophen would reduce the typical delay in disengaging from emotional expressions. Our findings showed a significant main effect of facial expression, with happy faces producing the greatest delay, but there was no difference in response between the acetaminophen and placebo conditions. These results indicate that acetaminophen does not alter our initial assessment of emotional facial expressions, but we suggest further research be conducted to examine how this widely consumed drug may alter the detection and perception of emotions in others.