There's a new guy in town, and he has the longest eyelashes you've ever seen, perfectly smooth skin, and pretty lips that set your heart a-flutter.

If you've ever fallen for a man with feminine features, you may have come succumbed to what's known as the "Johnny Depp Effect".

The tendency for women to be attracted to men with softer features, rather than craggy, macho types, has long intrigued researchers, and scientists now believe there is more to the story than meets the eye.

In studies by the University of Otago, Warwick Business School, and the University of California, San Diego, researchers asked volunteers to rate the attractiveness of gender-blended faces.


While the findings showed an overall preference for more feminine features, another interesting pattern emerged: People always judged an ambiguous face as less appealing when they were asked to define the gender first.

Study co-author Professor Jamin Halberstadt, of the Otago University Department of Psychology, puts the pattern down to "processing fluency", the ease with which we can perceive, process, and categorise something.

"The idea we tested is that the mental effort of having to assign a gender to an ambiguous face has a flow-on effect of negatively influencing how we feel about that face," says Professor Halberstadt.

Piotr Winkielman, from the Warwick School of Business and UCSD, adds that "mental effort can negatively colour our initial impressions, even for things that are objectively pretty."

Researchers say the findings, published in the international journal PLOS ONE, can help to explain why feminine features are preferred in some contexts, but not others.

So, could those universally hard to define "rules of attraction" be affected by something as simple as how much brain power we have to use to define a face?

"It has previously been suggested that a woman's preference in male faces vary due to hormonal influences - that sometimes she is subconsciously looking for signs of a 'nice dad' who will be a good provider, while other times it is the highly masculine 'bad boy' with his 'better' genes," says Professor Halberstadt.

"However, our research indicates that such changes in preferences can instead be explained by a simple cognitive process."