Now, it is possible to accurately predict first impressions using physical features in everyday facial images such as those found on social media, says a study.
"The findings show how important faces and specific images of faces can be in creating a favourable or unfavourable first impression," said Richard Vernon, a Ph.D. student part of the research team at University of York's department of psychology.
When we look at a picture of a face, we form judgements about a person's character, for example whether they are friendly, trustworthy or competent.
Even though it is not clear how accurate they are, these first impressions can influence our subsequent behaviour.
"The impressions we create are becoming more important in a world where we increasingly get to know one another online rather than in the flesh," researchers noted.
Researchers took ordinary photographs from the web and analysed physical features of the faces to develop a model that could accurately predict first impressions.
Each of the 1,000 faces was described in terms of 65 different features such as "eye height", "eyebrow width" and so on.
By combining these measures, the model could explain more than half of the variation in human raters' social judgments of the same faces.
"We make first impressions of others so intuitively that it seems effortless - I think it is fascinating that we can pin this down with scientific models," explained Ph.D. student Clare Sutherland.
The study was published in Proceedings of the National Academy of Sciences (PNAS).
