The research team found that people find familiar faces more attractive than unfamiliar ones. They also found that the human brain holds separate images of both male and female faces and reacts to them differently depending on how familiar it is with their facial features.
Dr Anthony Little, from the University's School of Biological Sciences, examined whether early visual experience of male and female faces affected later preferences. The research team asked over 200 participants to view a number of human faces that had been digitally manipulated to change their facial characteristics.
Dr Little said: "We found that participants preferred the face that they were most visually familiar with. In one of the tests we showed participants a block of faces with wide-spaced eyes and then asked them to compare these with a face that had narrow-spaced eyes. We found that participants preferred the face with wide-spaced eyes, suggesting that the brain connects familiarity with attraction."
The team also asked participants to judge the same preferred facial features in those of the opposite sex. Participants who were shown male faces with wide-spaced eyes preferred this trait in subsequent male faces but not in female faces.
Dr Little explains: "The research revealed that the sex of the face can be a deciding factor in facial preference. The tests showed for the first time that the brain holds separate visual patterns of male and female faces and responds to them based on their sex as well as their familiarity. We will continue to investigate why this is the case."
"The next step in the research is to find out why the brain makes a link between familiarity and attractiveness. It maybe that visual experience of particular facial features suggests that a person is 'safe' or more 'approachable', both of which are desirable traits."
Dr Little's research, in collaboration with University of St Andrews and University of Aberdeen, will be published by Proceedings of The Royal Society - Biological Sciences this week.
Notes to editors
1. Members of the public are invited to take part in the on-line facial attractiveness study by logging on to www.alittlelab.com
2. The University of Liverpool is one of the UK's leading research institutions. It attracts collaborative and contract research commissions from a wide range of national and international organisations valued at more than £90 million annually.