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Research published in the Journal of Personality and Social Psychology shows that sex ratios, or the percentage of men and women, have a larger effect on our decisions than we think, including finding that men may pay more for a date or engagement ring when there are fewer women around.

In the first study, "The Financial Consequences of Too Many Men: Sex Ratio Effects on Saving, Borrowing and Spending," published in January 2012, lead author Vlad Griskevicius, marketing and psychology professor at University of Minnesota's Carlson's School of Management, and his co-authors conducted two experiments.

In a laboratory study of about 600 people, when male college participants were told there was a scarcity of women on their campuses and in other areas of their lives, they were willing to pay $6.01 more on average for Valentine's Day gifts and $278 more for an engagement ring than men who were not told of a supposed scarcity of the opposite sex.

"What's always been interesting to me is people in the study are unaware that sex ratio has any affect on their preferences," Griskevicius said. "They just feel like an engagement ring should cost a particular amount, but they have no idea what's causing them to feel that way."

In the a second analysis in the paper, the researchers conducted a data study of 143 U.S. cities. In places where women were more "scarce," men cut their savings rate by 42 percent and they increased their credit card debt by 84 percent.

However, the researchers found that sex ratios did not seem to correlate with women's financial practices.

Though women's finances did not directly seem to be related to sex ratios, Griskevicius hypothesized that the scarcity of the opposite sex has an effect on women's other choices, such as career decisions.

In a follow-up study published last month, called "Sex Ratio and Women's Career Choice: Does Scarcity of Men Lead Women to Choose Briefcase Over Baby?" Griskevicius and his co-authors asked female college participants about their career and family decisions.

To one group, the researchers told the participants that there were fewer men in their communities, showed them photos with more women than men and altered news articles to show a scarcity of men. Those women more often chose high-paying careers than the women who were not shown a scarcity of men.

The Labor Department's list of top paying careers for females includes medicine, law among other lucrative careers.

"Accordingly, this low-male sex ratio produced the strongest desire for lucrative careers in women who are least able to secure a mate," the paper said. "These findings demonstrate that sex ratio has far-reaching effects in humans, including whether women choose briefcase over baby."

Griskevicius said the second paper received a more "fiery" reaction than the first.

"People are going to be offended by this," he said, adding that some women have called the research "sexist" and claimed that their career choices have nothing to do with potential mates.

On the other hand, he said some "career women" have acknowledged the research may have a grain of truth.

The "underlying response," Griskevicius said, "is that people are often unaware of how … number of men and women in the workplace or on campus [is] changing their preferences."