“Attitudes toward beauty are entwined with our deepest conflicts surrounding flesh and spirit,” Harvard’s Nancy Etcoff wrote in her indispensable meditation on the psychology of beauty. But beauty’s primal appeal and its polarizing power on our inner world has a dark side. In a chapter unambiguously titled “Why Playboy Is Bad for Your Mental Mechanisms” from his altogether engrossing book Sex, Murder, and the Meaning of Life: A Psychologist Investigates How Evolution, Cognition, and Complexity are Revolutionizing our View of Nature (public library), Arizona State University psychology professor Douglas T. Kenrick explores how overexposure to beauty makes us recalibrate our own criteria for what is beautiful to a point that harms human relationships and even our experience of love.

He describes a curious experiment inspired by his own everyday experience as a graduate student twenty years earlier, when he caught himself noticing a disproportionate number of attractive female students in the crowd passing by during campus rush hour. Fascinated by this phenomenon of extreme selective attention when it comes to beauty, Kenrick decided examine it empirically two decades later as a formal researcher and replicated his youthful ogling in an experimental setup:

When we strained our subjects’ attentional capacities, we found exactly what I had suspected several decades before: Men overestimated the number of beautiful women (though their estimates of handsome men were unaffected). Female subjects also overestimated the frequency of gorgeous women in the rapidly presented crowds, but they did not overestimate the frequency of handsome men. The whole body of findings points to a simple conclusion about beautiful women: They capture everyone’s attention and monopolize downstream cognitive processes. The conclusion about handsome men is different: They grab women’s eyes but do not hold their minds; good-looking guys quickly get washed out of the stream of mental processing.

But pointing to other research he has conducted with his colleague Sara Gutierres, Kenrick argues that “an overdose of beauty might have ill effects for both sexes, albeit different ones for women than for men.” Citing Harry Helson’s famous 1947 theory of sensory adaptation, which holds that we make psychological adjustments as we match new forms of stimulation — hot or cold, salty or sweet, heavy or light, etc. — against our adaptation level, he began suspecting that sensory adaptation might be at work when it comes to our judgments of beauty. So Kenrick and Gutierres set out to test the idea:

In our first study, [we] asked people to judge an average-looking woman after being exposed to one of two series of other women. Half the participants judged the target woman after seeing a series of unusually beautiful women; the other half judged her after seeing a series of average-looking women. As in the case of expose to extremes of water temperature, exposure to extremes of physical appearance affected people’s judgments of what was average. As we had predicted, an average-looking woman was judged significantly uglier than normal if the subjects had just been gazing at a series of beauties.

Another study sought to assess whether these same processes played out in our judgments of people we know and love. Under the pretext of conducting research on “community standards of aesthetic judgment,” the scientists told participants they were collecting opinions from a random sample of students to settle an ongoing controversy about what is considered good and bad taste in visual art:

Subjects in the control group first judged the artistic merit of abstract paintings such as Josef Albers’s Homage to the Square. The men in the experimental group saw centerfolds from Playboy and Penthouse; the women saw handsome naked men from Playgirl. After they had looked at either paintings or centerfolds, we asked our participants to rate their feelings about their current relationship partners. Again, there was a cover story — that psychologists were divided on whether being in a relationship opened people up to new aesthetic experiences or made them less open to novelty. To test which side was right, we told them, we needed to know about the extent to which their reported level of commitment depended on whether they had seen centerfolds.

Once again, the results displayed a curious gender difference:

Men who had viewed the centerfolds rated themselves as less in love with their partners; women’s judgments of their partners were not so easily swayed.

What the study suggests is at once obvious and ominous: Exposure to beautiful women changes people’s reference points for what is beautiful. Kenrick considers the implications for men:

The harmful side effect for guys … is this: Real women … do not look as attractive once the mind has been calibrated to assume the centerfolds are normal. And for guys in relationships, exposure to beautiful photos undermines their feelings about the real flesh-and-blood women with whom their lives are actually intertwined.

(It turns out, then, that Esquire’s 1949 dating tips were not only amusingly appalling in their sexism, but also scientifically off in advising women to only bring their most glamorous friend to a double date.)

But lest we’re too quick to assume men are the only ones who conform to the worst of their gender’s stereotypes, women didn’t fare much better when the experiment was repeated with power rather than beauty as the variable:

Seeing a series of socially dominant men undermined women’s commitment, just as seeing attractive women had done to men’s.

But what could be driving this toxic allure of beauty? Kenrick suggests a biological basis for our sensory receptors, which evolved to make our ancestors aware of opportunities and threats while looking for mates in a world very different from our own — but amidst today’s media overstimulation, he argues, our natural mechanisms are overwhelmed and begin to malfunction. He likens our relationship with beauty to our relationship with food:

In a sense, the images from Hollywood and Madison Avenue are analogous to the flavors of Ben & Jerry’s ice cream. The tasty flavors and images tap into mechanisms that were designed to promote survival and reproduction in a much different world. Consume too much, though, and it may be harmful to your health.

Like Clay Johnson did in his information diet guide, Kenrick suggests a cure that is at once obvious and onerous, simple but certainly not easy, and altogether necessary for the sake of sanity:

So what’s a mortal to do? Are we helpless in the face of our evolved mechanisms, which may lead us astray without our conscious awareness? Not completely. People who understand the dangers of overabundant fats and sugars can control their diets. People who understand the dangers of an overabundant diet of mass-media images can stop gorging on Playboy, People, Sex and the City, or Dancing with the Stars.

It may sound simplistic, perhaps, but at the heart of this empirically grounded suggestion is the idea that our beauty diet is just one of the harmful habit loops we can rewire if we remember that, as William James famously put it, “we are spinning our own fates, good or evil, and never to be undone. Every smallest stroke of virtue or of vice leaves its never so little scar.”

Sex, Murder, and the Meaning of Life is absolutely captivating in its entirety, exploring such fascinating subjects as the relationship between sex and religion, the psychology of homicidal fantasies, and the missing bricks in Maslow’s classic pyramid of needs.