Whether or not porn "addiction" literally damages the brain, even brief viewing of pornographic images does interfere with people’s “working memory”—the ability to mentally juggle and pay attention to multiple items. A study published last October in the Journal of Sex Research tested the working memory of 28 healthy individuals when they were asked to keep track of neutral, negative, positive, or pornographic stimuli. “Results revealed worse working memory performance in the pornographic picture condition,” concluded Matthias Brand, head of the cognitive psychology department at the University of Duisburg-Essen, Germany.

One myth about sex—or perhaps it’s just a joke?—is that “testosterone poisoning” makes young men stupid. Actually, a 2007 study in the journal Neuropsychologia measured the level of testosterone in the saliva of prepubertal boys, including some who were intellectually gifted, with an IQ above 130, some who were average, and some who were mentally challenged, with an IQ less than 70. They concluded that “boys of average intelligence had significantly higher testosterone levels than both mentally challenged and intellectually gifted boys, with the latter two groups showing no significant difference between each other.”

But if having sex can make people smarter, the converse is not true: being smarter does not mean you’ll have more sex. Smarter teens, in fact, tend to delay their initiation of coital activities. A 2012 study by researchers at the University of Pennsylvania found that high working memory decreases the likelihood of early adolescent sexual debut. Some researchers have attributed the delay to greater overall “competence” among smarter teens. But a 2010 study found that adolescents at both the upper and lower ends of the intelligence distribution were less likely to have sex. Most recently, a study of 536 same-sex twin pairs concluded that intelligence may be a red herring: the association is really between school achievement, not IQ per se, and age at first sexual experience.

In old age, too, cognitive abilities affect one’s chances of getting lucky. A study published just last month found that older adults with mild cognitive impairment (MCI), often a forerunner of Alzheimer’s disease, were only about half as likely to have engaged recently in sexual activity as were their cognitively healthy peers. Of those with MCI, just 32.5 percent had recently engaged in sex, compared to 62.3 percent of those without MCI.

Perhaps, however, the dream of getting smarter through sex is just an alluring fantasy. Tracey J. Shors, a psychologist at the Center for Collaborative Neuroscience at Rutgers University, has reported that while many activities can increase the rate at which new brain cells are born, only effortful, successful learning increases their survival. As she said at a meeting on “Cognitive Enhancers” at the Society for Neuroscience in 2012: “You can make new cells with exercise, Prozac and sex. If you do mental training, you’ll keep alive more cells that you produced. And if you do both, now you have the best of both worlds—you’re making more cells and keeping more alive.”