Actual study here
In the “bikini” experiments, Belgian researchers conducted a series of tests on 358 young men. In one test, the men looked at images of women in bikinis or lingerie and at images of landscapes. In another, some men were given T-shirts to handle and assess while others were given bras. Another batch of men was assigned to watch a commercial featuring men running over landscapes while other guys watched a video of “hundreds of young women, dressed in bikinis running across hills, fields and beaches.” (No word on whether they used “Baywatch” slo-mo).
In each test, the researchers offered the men the choice between being paid 15 euros immediately or bargaining for a larger sum that they'd be willing to wait a week or a month for. In all the tests, the men exposed to the sexy imagery or bras cited delayed reward amounts that were lower than the amounts cited by the men who saw sex-neutral imagery. For example, while a man who looked at landscapes might have demanded an extra payment of 10 euros a month later (totaling 25), the bikini-gazer might have been willing to settle for five extra (totaling 20). The sexy imagery did not work on all men all the time, but, as a group, men with sex on their brains settled for a less lucrative bargain, suggesting they were more impulsive and valued immediate gratification more than the controls.
“I observed in my studies that men are more likely to pick a smaller immediate reward over a larger later reward,” Bram van den Bergh, the study’s lead author, tells me. “Hence I do think that men might spend money on something they might otherwise not purchase. Men would become more impulsive in any domain after exposure to sexual cues.”
Sexy ‘tunnel vision’
This jibes with the findings of a 2006 paper, “Heat of the Moment: The Effect of Sexual Arousal on Sexual Decision Making.” George Loewenstein of Carnegie Mellon University and Dan Ariely of MIT, found that sexually aroused men would do all sorts of things they might not otherwise do.
To study this effect, they asked men to masturbate while answering a series of questions on a computer. (They helpfully created a system that could be operated with one hand.) For example, 42 percent of non-aroused men thought women’s shoes were erotic. But 65 percent of aroused men thought so. Nineteen percent of non-aroused men said they would agree to sex in a threesome with another man and a woman, while 34 percent of aroused men said so. Less than half, 46 percent, of non-aroused men said they would encourage a date to drink to increase the chance she would have sex with them, but 63 percent of aroused men said so.
Loewenstein, one of the founders of the field of neuroeconomics, which links the workings of our brains to economic and other human interactions, sometimes using machines like functional magnetic resonance imaging to literally watch brain regions light up, says that sex and other strong drives “produce a kind of tunnel vision.”
“Drives are designed to motivate you to focus on specific goals; they have evolved for that purpose, to focus on the goal to the exclusion of other goals or considerations,” he says.
So a man who is aroused literally narrows his view of the world. When we’re thinking about sex, pretty much all we can think about is sex. So a man might do things he would not otherwise do (spending an hour surfing a Jennifer Love Hewitt fan site), or may behave in a seemingly irresponsible manner (skipping the condom).
In fact, studies have shown that sexy ads don’t really make men remember the product. We’re so lasered in on the sexy stuff, we don’t care what brand of beer it is, or how long it takes the car to go from zero to 60.
What about a Beckham effect?
None of this excuses bad boy behavior, but it may help women understand why even a choir boy is tough to dissuade once he’s built up a head of steam.
Whether or not women are as blinded by sex as men remains an open question. Would a picture of David Beckham in briefs influence a woman to pass up a bigger payout? Maybe, but the studies on sexual arousal and decision-making have mostly been done on men, so the verdict is out.
In general, though, all our brains, Loewenstein believes, can be thought of as being of “two minds,” there is the “affective system,” (“Dude! Who cares what it costs! She’s hot!”) which answers to our basic drives, and the deliberative system (“That’s your IRA contribution!”). To think of this another way, picture an angel on one shoulder and the devil on the other. Even in the heat of the moment, there is still that little voice that says "You know you are making a mistake" — the trouble is it gets drowned out by the volume of the affective system.
We are constantly negotiating between these two systems, which is why economists are so interested; it’s how we make purchasing decisions. It may also explain the morning-after walk of shame, the overcharged credit card — and “don’t worry, I’ll pull out in time.”
So bikinis ring our affective bells and those things make a lot of noise. Just remember this when you go to the beach, or the pool, or the lake this summer. She may look amazing in that tiny bikini, but try to listen to that little voice that’s whispering “SPF 30,” no matter how uncool you’ll look slathering it on.
tldr; A study showed that men that are exposed to sexually-arousing images during decision-making consistently make worse decisions. They settle for crappier deals that are focused on short-term gain, do irresponsible things, and behave in ways they otherwise wouldn't. Their perception also changes and they find things attractive where they wouldn't find them attractive while not aroused.
This is actually pretty interesting. Turns out there is a scientific basis for one of the most common stereotypes in modern culture. People often joke about how that beer commercial with hot women in it won't make anyone buy that beer, or having semi-naked women in bikinis to showcase that new concept car won't sell it. But turns out it helps... a lot. Perhaps you should wear a bikini before arguing with your boyfriend? Hmmm...
But what is actually intriguing to me is that this sexual drive must have evolved, and along with it, women's taking advantage of this sexual drive might have evolved? (read: is sexual manipulation a partially hardwired behavior?)
After all, if your gender has the ability to manipulate the opposite gender in some way and this gives you an evolutionary advantage (i.e. getting your way: money, social status, power, bearing the children of the tribe's chief, etc.) then those members that use the ability will be better at surviving and reproducing, and those who don't will be worse at it. Over hundreds of thousands of years you'll end up with women who are more adept at sexual manipulation than before, and men who are more vulnerable to it (no, i don't suggest all women are manipulative whores, so don't even try it).
Now the big question is whether the so-called "Beckham- effect" exists; do women make worse decisions when sexually aroused? If they do I think we will have caught a glimpse at the fundamentals of the intergender sexual arms race.
edit: part about evolution fixed. sorry about the bad wording.
edit 2: posted the actual study because you people are too fucking lazy to spend 5 seconds on google.