Experiments with Control Substances

Abstract

Little is known of the pharmacology of the "placebo", partly because there are so may different kindsof placebo which vary in their actions, and partly because there are so many kinds of individuals to react to them. Placebo reactors can be divided into "positive reactors", who produce reactions in the desired or therapeutic direction, "negative reactors", who react in a way opposed to that desired, and "non-reactors", who show no effect at all. Reactors are more aware of social pressure, more extroverted less dominant, and more neurotic than non-reactors. They are also less self-confident and show a greater expectancy that the "drug" will be effective. Modes of presentation of active drugs and placebos in clinical trials are also important. The effect of the administration of a drug in hospital may differ from that of a drug administered in general practice because the former is given to a patient who is one of a group, and the latter to an individual acting alone.