title: Amphetamine as a social drug: effects of d-amphetamine on social processing and behavior.
abstract: BACKGROUND
  Drug users often report using drugs to enhance social situations, and empirical studies support the idea that drugs increase both social behavior and the value of social interactions. One way that drugs may affect social behavior is by altering social processing, for example by decreasing perceptions of negative emotion in others.
  
  
  OBJECTIVE
  We examined effects of d-amphetamine on processing of emotional facial expressions and on the social behavior of talking. We predicted amphetamine would enhance attention, identification, and responsivity to positive expressions, and that this in turn would predict increased talkativeness.
  
  
  METHODS
  Over three sessions, 36 healthy normal adults received placebo, 10, and 20 mg d-amphetamine under counterbalanced double-blind conditions. At each session, we measured processing of happy, fearful, sad, and angry expressions using an attentional visual probe task, a dynamic emotion identification task, and measures of facial muscle activity. We also measured talking.
  
  
  RESULTS
  Amphetamine decreased the threshold for identifying all emotions, increased negative facial responses to sad expressions, and increased talkativeness. Contrary to our hypotheses, amphetamine did not alter attention to, identification of, or facial responses to positive emotions specifically. Interestingly, the drug decreased the threshold to identify all emotions, and this effect was uniquely related to increased talkativeness, even after controlling for overall sensitivity to amphetamine.
  
  
  CONCLUSIONS
  The results suggest that amphetamine may encourage sociability by increasing sensitivity to subtle emotional expressions. These findings suggest novel social mechanisms that may contribute to the rewarding effects of amphetamine.
authors.affiliation: Department of Psychiatry and Behavioral Neuroscience, University of Chicago, 5841 S. Maryland Ave., MC 3077, Chicago, IL 60637, USA.
authors.forename: Margaret C
authors.initials: MC
authors.lastname: Wardle
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Garner
authors.forename: Marcus R
authors.initials: MR
authors.lastname: Munafò
authors.forename: Harriet
authors.initials: H
authors.lastname: de Wit
mesh_terms: D000293:Adolescent; D000328:Adult; D000661:Amphetamine / Q000494:pharmacology*; D000697:Central Nervous System Stimulants / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D004644:Emotions / Q000187:drug effects*; D005149:Facial Expression; D005152:Facial Muscles / Q000187:drug effects; D005260:Female; D006801:Humans; D008297:Male; D009483:Neuropsychological Tests; D010364:Pattern Recognition, Visual / Q000187:drug effects; D010775:Photic Stimulation; D012684:Sensory Thresholds; D012919:Social Behavior; D014705:Verbal Behavior / Q000187:drug effects*; D055815:Young Adult
chemical_list: D000697:Central Nervous System Stimulants; D000661:Amphetamine