Biological scientists at the University of Liverpool launched the study to investigate the reasons why many couples tend to look similar to each other. The team, in collaboration with the University of Durham and the University of St Andrews, asked participants to judge perceived age, attractiveness, and personality traits of real-life married couples. Photographs of female faces were viewed separately to male faces, so that participants were unaware of who was married to whom.
Dr Tony Little, from the University's School of Biological Sciences, explains: "There is widespread belief that couples, particularly those who have been together for many years, look similar to each other. To understand why this happens, we looked at the assumptions that people make about a person's personality, based on facial characteristics. We found that perceptions of age, attractiveness and personality were very similar between male and female couples. For example if the female face was rated as 'sociable' then her partner was also more likely to be rated as 'sociable.'
"We also found that couples who had been married for a long period of time, were perceived as having more similar personalities than those who had not been together very long. This may come from sharing experiences together - affecting how their face appears."
Scientists are now looking for people who are both single and attached to take part in an online study that will include questions about their personality, age and how they rate their own attractiveness. The study will also feature face preference tests, in which participants will be asked to rate the attractiveness of different face types. The online study will examine whether an individual's physical and personality traits influence their face preferences.
Scientists will also investigate whether face perceptions are different between those with and without partners.
Dr Little added: "These tests will allow us to see how particular face types communicate certain personality traits and how perceptions of unfamiliar faces, as well as our own face, influence us in the friends and partners we choose."
Members of the public are invited to take part in the online face experiments by logging on to www.alittlelab.com