I didn't bother to look up the primary literature, but check Scientific American...

rlb13 on June 9, 2015 | parent | context | favorite | on: Placebo Button

I didn't bother to look up the primary literature, but check Scientific American, March 2015, article by Kevin Tracey, pp. 30-35. As always, don't blame the named author for all the fluff added for the general reader.