According to Gibbs (2010), placebos are interventions that do not have a true treatment effect on the symptom or disease for which they are used. An important aspect is that people think they receive a true treatment.
Even though people receive no treatment, they may show a placebo effect. In short, a placebo effect is seen an alleviation of symptoms, despite the fact that people do not receive a treatment. In other words, the alleviation of symptoms must rely on other mechanisms than the treatment mechanisms (i.e., medicine).
The placebo effect may work through various psychological processes: classical conditioning, patient expectancy, and the patient’s desire for a favorable treatment outcome. Often, there is seen a neurobiological or immunological basis for the placebo effect (Gibbs, 2010).
The placebo effect is therefore considered to be as “real” as a real treatment outcome. Sometimes, placebo effects elicit therapeutic effects that are equivalent to real treatment effects.
A placebo condition is used in clinical research for two main reasons. The first is to ensure blinding procedures of both patients and researchers, i.e. double blind. The second is to observe differences between the true treatment effect and the placebo effect (Gibbs, 2010).
If there is no observed difference between a treatment group and a placebo group, a given treatment is considered ineffective. Placebo groups are therefore useful for evaluating the effects of given treatments.
The placebo-effect may occur when a person expects a given treatment outcome. So, the placebo-effect is a mental phenomenon with physical consequences. That is how powerful the mind is.