Jonah Lehrer - Porn and Mirror Neurons

Jonah takes on the industry that has been building up around mirror neurons. I don't agree with all of it, but Jonah makes some good points.

Porn and Mirror Neurons

Posted on: August 24, 2009 12:45 PM, by Jonah Lehrer

Mirror neurons are a classic illustration of a scientific idea that's so elegant and intriguing our theories get ahead of the facts. They're an anatomical quirk rumored to solve so many different cognitive problems that one almost has to be suspicious: how can the same relatively minor network of motor neurons be responsible for tool use, empathy, language and be a core feature of autism?

I'm not saying that mirror neurons don't have the potential to be an astonishingly cool cortical feature, especially when it comes to the intuitive understanding of physical actions. But I have yet to be even close to convinced that they will do "for psychology what DNA did for biology: provide a unifying framework and help explain a host of mental abilities that have hitherto remained mysterious and inaccessible to experiments." For one thing, mirror neurons have been most convincingly studied in monkeys, which makes them an unlikely candidate to explain a host of uniquely human talents.

That said, I do think there's good initial evidence that mirror neurons play an important role in helping us decipher the meaning of another person's movements. Consider porn, which is a very big business. (I first wrote about the neuroscience of porn a long time ago, but I think it's worth repeating some of that post, since porn is such a perdurable feature of civilized life.) When you include Internet Web sites, porn networks and pay-per-view movies on cable and satellite, phone sex, and magazines, the porn business is estimated to total between $10 billion and $14 billion annually. As Frank Rich has noted, "People spend more money for pornography in America in a year than they do on movie tickets, more than they do on all the performing arts combined." Sex sites are estimated to account for up to thirty percent of all Internet traffic.

But how does porn work? Why do humans (especially men) get so excited by seeing someone else have sex? At first glance, the answer seems obvious: watching porn triggers an idea (we start thinking about sex), which then triggers a change in our behavior (we become sexually aroused). This is how most of us think about thinking: sensations cause thoughts which cause physical responses. Porn is a quintessential example of how such a thought process might work.

But this straightforward answer is probably wrong. Porn does not cause us to think about sex. Rather, porn causes to think we are having sex. From the perspective of the brain, the act of arousal is not preceded by a separate idea, which we absorb via the television or computer screen. The act itself is the idea. In other words, porn works by convincing us that we are not watching porn. We think we are inside the screen, doing the deed.

Mirror neurons facilitate this process by allowing the brain to automatically imitate the actions of somebody else. So if I see you smile, or lick an ice cream cone, or do something X-rated, then my mirror neurons light up as if I were smiling, or licking an ice cream cone, or doing something X-rated. We mirror each others movements, which allows us to make sense of all these flailing limbs and contorted muscles; the body is a pretty tough thing to read.

Obviously, this is all just idle speculation. Nobody has shown monkeys some primate sex tapes and recorded from their mirror neurons. (Sounds like a fun experiment to me!) But there is one paper, published in Neuroimage, that looked at the neuroanatomy of porn. The researchers flashed images of aroused genitalia to both men and women, heterosexuals and homosexuals. As expected, brain activity correlated with sexual preference: the minds of homosexual men mirrored the minds of heterosexual women, and vice-versa. But what was really interesting was the pattern of activation itself. When subjects looked at porn in the fMRI machine (not a very erotic place), "the ventral premotor cortex which is a key structure for imitative (mirror neurons) and tool-related (canonical neurons) actions showed a bilateral sexual preference-specific activation, suggesting that viewing sexually aroused genitals of the preferred sex triggers action representations of sexual behavior." In other words, looking at still pictures of naked people triggered our mirror neurons into action, as the brain began pretending that it was actually having sex, and not just looking at smutty pictures in a science lab.

Obviously, a similar logic can be applied to a range of other actions that people love to watch, such as sports, which I've written about here.

Tags: Jonah Lehrer, Porn and Mirror Neurons, The Frontal Cortex, Psychology, brain, research, neuroscience, fMRI