frogprince - check out the BBC iPlayer and look for the Horizon programme on Placebo - it will open your eyes. Specifically on knowing it is a placebo.

If you think about it there are words in the English language to point to the very real phenomenon. viz placebo, hyperchondria, psychosomosis, mind over matter, visualisation, hypnosis, meditation, and something that has been known since doctors were invented "Doctors bedside manner". And more contentiously IMNSHO I include homeopathy.

And the programme clearly shows research that the physician's approach as a big part of the success of any medical consultation. But the brain scans were quite revealing - there is a real physiological effect going on there.

I can't mend a broken bone, but it may reduce the pain you percieve.