Drinkers were asked to assess photos of females
The effect of "beer goggles" should not be used as an excuse for men getting a woman's age wrong, a study suggests.
University of Leicester researchers showed 240 people, half of whom had been drinking, digitally-altered images of females meant to be 13, 17 or 20.
The paper for the British Journal of Psychology said most overestimated ages no matter how much they had drunk.
The researchers say it suggests men who have sex with under-age girls should not be able to use drink as a defence.
But one expert said the paper did show young girls wearing make-up could mislead observers about age, even when they were stone cold sober.
Men accused of having unlawful sex with a minor sometimes claim they were not aware that the girl was under-age.
The idea of "beer goggles" was first identified by scientists in the early 1990s when it was dubbed "alcohol myopia".
Dr Vincent Egan, the psychologist who led this latest research, said he had come across a number of cases where men had used this defence.
He decided to investigate how people did respond to images of women at different ages.
The study involved 120 sober men and women, and 120 who were drinking in pubs. All were aged between 18 and 70.
Drinkers also had their blood alcohol levels measured - a third could be classed as drunk.
Dr Egan and his team took a picture of a 17-year-old and digitally manipulated it to show how the girl would look aged 13 and 20.
Some of the photos of the 17-year-olds were also treated to look as if they were wearing make-up.
The researchers found no difference in age estimates between drinkers and non-drinkers - there was a consistent overestimation of the women's ages.
Dr Egan said: "Even at considerable levels of drunkenness, males are not disproportionately impaired in estimating the age of made-up immature female faces.
"The notion of 'beer goggles' is therefore irrelevant, and it might be there's a pre-existing bias rather than having any links to drink."
The only strong effect the team found was people assessing made-up faces as older, but they said that was also consistent between drinkers and non-drinkers.
He added: "There is a public perception that drinking alcohol affects how age is judged.
"But people are always seeking excuses for the bad things that they do."
He said the findings of this study might mean juries and courts challenged the argument used by some defence solicitors that alcohol can affect judgement in under-age sex cases.
Tim Valentine, a professor of psychology at Goldsmith's University in London, said: "The results do not support the contention that alcohol consumed by the accused would lead him to judge the girl as appearing older. Therefore, the research does not support this defence.
"However, the research does show that younger faces with make-up look older and that people generally overestimate the age of teenage girls.
"Therefore the research provide some scientific support for the defence that the accused believed that the girl was older than she actual was.
"Whether this is actually a defence is an issue for a lawyer, not a psychologist."