Telling a prospective partner “I really like you” is likely to encourage the chosen target to reciprocate the feelings.
Research revealed that if a person shows someone their feelings, through eye contact, smiling – or simply telling them – they are more likely to return the sentiment.
Previous research has emphasised natural beauty and physical features such as facial symmetry or voice pitch.
But the University of Aberdeen study shows the science of attraction to be more complex.
It found “social cues” – someone’s efforts to show how much they like a person – are of great importance in the blossoming of mutual attraction.
Psychologist Dr Ben Jones, one of the authors of the study, said: “Our latest research highlights how social cues, which signal the extent to which others are attracted to you, also play a crucial role in attraction.”
The study, Integrating Facial Attractiveness And Cues Of Social Attractiveness, was published in the journal Psychological Science.
Scientists showed volunteers four flash cards, picturing a face with different expressions.
The face is shown making eye contact and not smiling; not making eye contact and not smiling; making eye contact and not smiling: and making eye contact and smiling.
A total of 230 men and women took part in the study at the university’s Face Research Laboratory.
Dr Jones said: “What we found was that the preference for the attractive face was much stronger when people were judging those faces that were looking at them and smiling.”
Attractiveness, according to the study, was how someone combined natural beauty and these “social cues”.
Dr Jones carried out his research with Dr Lisa DeBruine, also of the University of Aberdeen.
The pair will present their research at the BA Festival of Science in Liverpool.