Alcohol blurs a person's ability to spot symmetry, say researchers.

The mystery of “beer goggles” — the phenomenon of people finding members of the opposite sex more attractive after just a few alcoholic drinks — has finally been solved.

Researchers at Roehampton University claim to have found that the beer goggles effect comes down to symmetry, or people's perception of symmetry after a couple of hours in a bar.

In other words, alcohol dulls the drinker's ability to recognise asymmetrical faces. “Alcohol affects our innate human ability to choose a mate. We tend to prefer faces that are symmetrical,” said team leader Lewis Halsey.

For their research, the team designed an experiment involving images of faces that were tinkered with to make them perfectly symmetrical or subtly asymmetrical. About 101 students, either sober or intoxicated, were then asked to state the faces they found the most attractive. They also had to determine if the faces were symmetrical.

The findings, published in the Addiction journal, revealed that sober students had a greater preference for symmetrical faces than intoxicated students.

Also, the researchers found that the sober students were better at detecting whether a face was symmetrical.

What's more, the data suggest that men are less prone to losing their symmetry-detecting ability when intoxicated than women. Mr. Halsey said the difference had to do with the tendency of men to be more visually oriented.

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