Question on experiments involving placebos

[Jean Edwards]

Hi all:   In experiments involving placebos, what are all the subjects/participants told? I was reading about a medical procedure reported in newsweek regarding surgery to relieve symptoms of Parkinson's disease. Some of the participants received the real operation; others a sham operation. Researchers found that those receiving the sham operation "benefited almost as much as those who had fetal cells implanted in their brains." Again, what are the subjects told? And.. I wonder what happens if the patients who receive the sham operation find out it was a sham.   Thanks in advance to those who reply.   JL Edwards [EMAIL PROTECTED]