title: Does alcohol consumption really affect asymmetry perception? A three-armed placebo-controlled experimental study.
abstract: OBJECTIVE
  A possible explanation for increased levels of attractiveness of faces when under the influence of alcohol is the reduced ability to perceive bilateral asymmetry. This study tested the degree of preference by alcohol-dosed and non-alcohol-dosed participants for symmetrical faces and their ability to detect facial symmetry, while controlling for other explanations.
  
  
  METHODS
  Volunteers were recruited to a random allocation experiment with three conditions: alcoholic drink (alcohol dosed), non-alcoholic drink (placebo) and diluted orange cordial (control). Data on concentration, personality and demographics were collected. Dependent variables were symmetry preference and detection.
  
  
  METHODS
  Laboratory, University of Roehampton.
  
  
  METHODS
  A total of 101 participants, mainly students (41 alcohol-dosed, 40 placebo, 20 control).
  
  
  METHODS
  Participants provided verbal responses to images of faces which were presented on a computer screen for 5 seconds each; the first task required a preference judgement and the second task consisted of a forced-choice response of whether or not a face was symmetrical. Levels of concentration, weight and level of alcohol dose were measured, and demographics plus additional psychological and health information were collected using a computer-based questionnaire.
  
  
  RESULTS
  In contrast to a previous investigation, there was no difference in symmetry preference between conditions (P = 0.846). In agreement with previous findings, participants who had not drunk alcohol were better at detecting whether a face was symmetrical or asymmetrical (P = 0.043). Measures of concentration did not differ between conditions (P = 0.214-0.438). Gender did not affect ability to detect symmetry in placebo or alcohol-dosed participants (P = 0.984, 0.499); however, alcohol-dosed females were shown to demonstrate greater symmetry preference than alcohol-dosed males (P = 0.004).
  
  
  CONCLUSIONS
  People who are alcohol-dosed are subtly less able to perceive vertical, bilateral asymmetry in faces, with gender being a possible moderating factor.
authors.affiliation: Department of Life Sciences, University of Roehampton, London, UK. l.halsey@roehampton.ac.uk
authors.forename: Lewis G
authors.initials: LG
authors.lastname: Halsey
authors.forename: Joerg W
authors.initials: JW
authors.lastname: Huber
authors.forename: Jennifer C
authors.initials: JC
authors.lastname: Hardwick
mesh_terms: D000428:Alcohol Drinking / Q000523:psychology*; D002492:Central Nervous System Depressants / Q000494:pharmacology*; D002755:Choice Behavior; D000431:Ethanol / Q000494:pharmacology*; D005145:Face; D005146:Facial Asymmetry; D005260:Female; D005556:Form Perception / Q000187:drug effects; D006801:Humans; D008297:Male; D011795:Surveys and Questionnaires
chemical_list: D002492:Central Nervous System Depressants; D000431:Ethanol