Most people prefer healthy-looking leaders over those who are more intelligent, according to a new study.

Intelligent leaders were only preferred when the position for which they were vying was one involving negotiations, or the development of new marketplaces. Otherwise, people chose to be ruled by the candidates with the best complexion.

A total of 148 volunteers, both men and women, were provided with pictures featuring pairs of male faces, and asked to imagine they were choosing a new CEO for a large corporation. Each of the sets of photographs were accompanied by a theoretical scenario, naming the biggest challenge facing the executive. Four scenarios were provided -- overseeing a company shift to green energy, facing stiff competition, negotiating a partnership with another corporation, or entering a new market.

Photos of the "pair" of candidates were digitally-enhanced photographs of single subjects, made to appear more or less intelligent, or which had their complexion altered.

"The researchers focused on facial traits in this study because these provide a wealth of information about individuals. For example, in women as well as men, caring and cooperative personalities are statistically more likely to have a more 'feminine' face, due to higher estrogen levels, while aggressive risk-takers tend to have higher testosterone levels and a more 'masculine' face," Vrije Universiteit Amsterdam researchers reported in a press release announcing the study.

Volunteers in the experiment chose the photographs of healthy-looking candidates over the pictures of more-intelligent looking candidates in 69 percent of the cases. This bias was especially noticeable in the two examples of managing the adoption of renewable energy technology and facing an aggressive competitor.

"Here we show that it always pays for aspiring leaders to look healthy, which explains why politicians and executives often put great effort, time, and money in their appearance," Brian Spisak of the VU University Amsterdam, said.

A group of 118 men and women were asked to judge photos prior to the experiment, to determine which digital manipulations added or deterred from the appearance of intelligence.

Prominent jawlines were seen as making the subjects in the photographs appear more masculine, and flushed, colorful skin was seen to create a look of good health. A healthy complexion was perceived by subjects in the study to contribute to perceptions of masculinity, while a look of intelligence was seen as feminine.

Investigation of the role played by the appearance of health compared with intelligence was detailed in the online, open-access journal Human Neuroscience.