Men are perceived as more masculine if they appear taller and heavier regardless of how much their face shape differs from a woman, a new study suggests.

Researchers at the University of St Andrews used three-dimensional scans of male and female faces to investigate the perception of masculinity.

They found that facial cues to body height and weight had "substantial and independent" effects on how men are seen.

Iris Holzleitner, lead author and PhD student at the university's Perception laboratory, said masculinity has powerful effects on attractiveness and a range of other attributions, such as leadership and trust.

"It is important that we understand the physical basis of perceptions and the origins of masculine stereotypes. Here, we showed that perceived facial masculinity has several distinct physical origins," she said.

"What is new about our study is that we tested whether cues to this individual variation in height and weight may be important when judging men's 'masculinity'.

"By comparing the face shape of very short and very tall men as well as that of very light and very heavy men, the researchers were able to determine facial correlates of body height and weight."

Professor David Perrett, of the School of Psychology and Neuroscience, who supervised the study, added: "We also asked people to judge the height and weight of the men in our sample - again just from their faces.

"We were surprised to found that the facial cues of height and weight we identified predicted perceptions of height and weight much stronger than actual height and weight."

He said the findings suggest people base their perceptual judgments on cues that are rooted in actual physical differences, but they go on to read too much into these cues.

"We seem to have learned that, for example, being tall is associated with a more elongated face shape. If presented with the faces of two equally-tall men, and one of them has a slightly longer face than the other, we will be likely to think that the man with the longer face is also taller," Prof Perrett said.

The authors of the study, published in scholarly journal Perception this week, think that this perceptual over-generalisation may also explain their main finding on masculinity.