M. Night Shyamalan, the director of the vaguely anti-evolution (and thoroughly mediocre) film The Happening, uses the brain to discuss the limits of science:
There’s so much unexplained stuff. I don’t quite understand the scientific explanation of the placebo effect. What is the core of that? The fact that the placebo effect exists is a fact, but what is it? We have no idea. I love that. I even love that with regard to the home-court advantage in sports. What is that? It’s connected to a belief system. Both things, the placebo and the home-court effect, are a belief system that we can turn thought into actual biological function. In and of itself, that’s something that science says is not possible. But you can document it.
On the one hand, I agree that science has real epistemological limits. And yet, the placebo effect – or any other example that involves a “belief system” or “thought” becoming “actual biological function” – is a terrible example of such limitations. There is nothing inherently mysterious about a psychological thought impacting the activity of neurons. That’s what thoughts do. (What else would they do? It’s like being amazed that my strokes on keyboard impact the activity of silicon microchips somewhere inside a computer.) As for the placebo effect…The precise mechanisms of the effect have been well documented.
Tor Wager, a neuroscientist at Columbia University, has probably done the definitive brain imaging study. His experiment was brutally straightforward: he gave college students electrical shocks while they were stuck in an fMRI machine. Half of the people were then supplied with a fake pain-relieving cream. Even though the cream had no analgesic properties – it was just a hand moisturizer – people given the pretend cream said the shocks were significantly less painful. The placebo effect eased their suffering. Wager then imaged the specific parts of the brain that controlled this psychological process. He discovered that the placebo effect depended on the prefrontal cortex, the center of “rational,” conscious thought. When people were told that they’d just received a pain-relieving cream, their frontal lobes responded by inhibiting the activity of the emotional brain areas (like the insula) that normally respond to pain. Because people expected to experience less pain, they ended up experiencing less pain.
I agree with Shyamalan that there is something inherently wondrous about the idea of conscious thoughts and ethereal daydreams being able to directly influence squirts of neurotransmitter and the electrical firings of neurons. But that’s only because we are natural dualists, innately programmed to believe in a metaphysical soul.