It's no secret that sex sells, but erotic ads may do more than make products sparkle: They may alter your economic decision-making in general. "If your brain's reward regions are activated at the moment of a decision—for example, through exposure to sexual cues—you become more likely to choose impulsively," says Bram Van den Bergh, a researcher at Katholieke Universiteit Leuven in Belgium.

Previous studies had shown that dirty thoughts make men more impulsive in the sexual domain—they discount the risk of STDs, for example—but Van den Bergh and collaborators demonstrated repercussions of "hot states" on decisions in nonsexual domains: Given the choice of 15 euros now or a larger chunk of change later, men who had just handled bras valued an immediate payoff more highly than did guys who'd been stuck fondling T-shirts. The research showed the same lingerie-induced myopia when the currency was sodas or candy bars. "Sexual desire leads to a desire to consume anything rewarding," Van den Bergh hypothesizes.

Because appetites for sex, money, and food appear to mingle in the brain, it could be that shopping with any craving will send you on a spending spree. Van den Bergh says the implications are clear. "If you're pondering fruit versus cake, or saving versus spending, make sure that sexual stimuli are absent, and that you're not desiring something at the moment." In other words, guys, don't bring your credit card to Victoria's Secret on an empty stomach.

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