How beautiful a person is depends on who they are standing with, researchers say.
A very normal looking face is seen as more beautiful when it is surrounded by faces that are considered "undesirable".
The study showed that a person can be ranked higher on a scale of attractiveness only when he or she is compared alongside a less attractive person, and not when being judged alone.
The company we keep can have an effect on how attractive we appear to others, the researchers said.
An averagely attractive face surrounded by undesirable faces will become more appealing than it would on its own.
"The presence of a less attractive face does not just increase the attractiveness of a single person, but in a crowd could actually make us even more choosey," said Nicholas Furl from Royal Holloway, University of London.
For the study, the team asked the participants to rate pictures of different faces for attractiveness, one by one.
They were then asked to assess the same faces, placed alongside ones perceived to be undesirable. When adding these "distractor faces", the attractiveness of the same faces increased from the first round of ranking.
Participants were then shown two attractive faces, alongside a "distractor" face and asked to judge between them.
The presence of the less attractive face was found to make the viewers more critical between the attractive face, the researchers explained.
"We found that the presence of a 'distractor' face makes differences between attractive people more obvious and that observers start to pull apart these differences, making them even more particular in their judgement," Furl said.
The study is published in the journal Psychological Science.
(With agency inputs)