Jonah Lehrer is a fascinating fellow. A contributing editor at Wired, he’s the author of Proust Was A Neuroscientist and How We Decide. I became familiar with him through his work on WNYC’s Radio Lab.

Today he got to thinking about mirror neurons:

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.”

Ok… And?

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…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.

For Jonah this was just today’s idle speculation. For more, he points us to this paper on the neuroanatomy of porn. (They find that brain activity correlates with sexual preference: the minds of homosexual men mirrored the minds of heterosexual women, and vice-versa.) Or, if you’d rather, here Jonah applies a similar logic to sports.

Bonus video (above), Lehrer’s February appearance on The Colbert Report.