It's amazing how thousands of drug studies find a sizable portion
of the benefits of a drug come from the power of suggestion.
For example, in a classic study, half of the medical students were given red pills they
were told were amphetamines (that really were sedatives). Half of these students
reported feeling a burst of energy. The other medical students were given 
blue pills they were told were sedatives (that were really amphetamines).
Half of them reported feeling calmer.

Because of the power of suggestion, credible drug studies must include a placebo
comparison group. On the average, placebo effects account for a third of the
benefits of treatments--whether the treatment is a medication or psychotherapy.

Research on optimism finds that optimisms are more successful and have better health.
For example, a study of men who had a heart attack found that eight years later 24%
of the optimists had died and 84% of the pessimists had died. Similar findings apply
to women with breast cancer. Martin Seligman rated essays by class of 1945-46
Harvard freshman found that at age 45 the optimisms were in good health but many
of the pessimists were developing health problems. By age 60 the difference was
even more pronounced.

I'm struck with how similar the power of expectations are with placebos and with
optimism. Similar forces are at work. With placebos, we have to be fooled.
With optimism, we only need to take a leap of faith.