Last week I wrote about how the placebo effect can have a potent effect on medical symptoms. The reason: the power of expectations. We expect to get better and so we do.

Here’s a related thought experiment. Suppose I’m a sommelier and someone orders a $20 bottle of wine and I serve it to them. Then another customer orders a $100 bottle of wine. Is it unethical for me to serve them the $20 bottle and tell them it’s the $100 bottle? What if they can’t tell the difference?

And here’s the real question: What if the person who thinks it’s a $100 bottle actually enjoys it more?

That's just what a team at Caltech and Stanford recently did, and brain scans confirmed that people don't just think the more expensive (but identical) wine tasted better—it actually really did taste better, as reflected by brain scans that showed their pleasure centers lighting up like Christmas trees. The phenomenon is called the price-placebo effect, and it, too, is fueled by the the power of expectations. Cognitive dissonance may also play a role: If you pay that much, you reason, it must be worth it, and the large psychological investment actually increases your satisfaction.