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Monday, April 2, 2012

Does alcohol consumption really affect symmetry perception? A three-armed placebo-controlled experimental study



A possible explanation for increased levels of attractiveness of faces when under the influence of alcohol is 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.

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.

Laboratory, University of Roehampton.

101 participants, mainly students (41 alcohol-dosed, 40 placebo, 20 control).

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 a face was symmetrical or not. 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.

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 to 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).

People who are alcohol-dosed are subtly less able to perceive vertical, bilateral asymmetry in faces, with gender being a possible moderating factor.



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