What Is the Placebo Effect? | Definition & Examples

The placebo effect refers to a phenomenon whereby patients experience an improvement in their physical ailment after taking a non-treatment, called a placebo.

The treatment contains no active ingredients, meaning that any improvement experienced by the patient is caused by their expectation or belief that the “treatment” is doing them some good.

In double-blind medical trials, where the experimental design includes both control and treatment groups, the placebo effect is often seen in the control group.

What is a placebo?

Depending on the treatment being used in the research, the placebo will be a sugar pill, a saline injection or infusion, or even a fake surgical procedure. The effect of the treatment being studied can be compared with any improvement in the control group, meaning that any improvement in the trial group over and above the progress of the control group can be attributed to the treatment.

A double-blind trial means that neither the researchers nor the patients know if they are receiving the placebo or the treatment. This means that there is no chance of the researchers inadvertently influencing the results.

Placebos can be effective in relieving symptoms like insomnia, fatigue, or pain, but they can’t actually “cure” anything as such, as they are not an actual treatment. Ethical guidelines often apply to their use, so it would be unlikely for a placebo to be given to a terminally ill patient, for instance.

Placebo effect definition

It is now well documented that taking a medication, whether it is a genuine treatment or a dummy one, will make many people feel better. This is called the placebo effect. It is thought that the patient’s belief in the treatment changes their perception of their symptoms. This is why pain, insomnia, and fatigue are areas where improvement is often seen with a placebo.

Once the placebo effect was understood, it made it easier to identify new treatments that were having a positive effect, as they needed to outperform a placebo to demonstrate that they were effective. If the two groups show similar improvements, then the experimental drug has been shown not to be effective.

Placebo effect examples

The placebo effect is an example of how the mind can exercise or stimulate changes in the body.

The placebo effect is also a way of understanding the anecdotal evidence we often hear about non-conventional treatments.

How does the placebo effect work?

The full answer to this question is still not known. But these factors are acknowledged as contributing to the effect:

• The placebo effect is more likely to be seen in those who are motivated to get better and expect to see improvement in their symptoms.
• Taking part in the study can lead to positive feelings about receiving care and attention. In itself, this can lower stress levels and stimulate the body’s own healing and pain-relief processes.
• Because taking medication is associated in our minds with getting better, classical conditioning means there is a link between treatment and improved health.
• Because of the nature of the study, the patients receive more attention from medical staff leading to a relationship of trust between them. This is conducive to the positive mindset needed for recovery.

It is not believed that the reasons behind the placebo effect are purely psychological. Some others include:

• Confirmation bias: If you are hopeful that a new treatment will bring you some relief, then you will be on the lookout for signs that the treatment is working.
• Regression to the mean: There is usually a time delay between the onset of symptoms and seeking medical help. And in the natural way of things, pain, along with other symptoms, will often decline over time without any intervention. This means the perceived improvement might just be the natural healing process.

Is there a downside to the placebo effect?

There is a phenomenon sometimes called the nocebo effect, which is when participants experience a negative outcome after taking a placebo. If a control group is warned about the possible side effects of a medication in the same way as the experimental group, then they may experience the same type and degree of side effects as those taking the trial drug itself, even though they are only taking a placebo.

Frequently asked questions about the placebo effect

What causes the placebo effect?

The placebo effect is most likely attributable to a number of causes, although no one is certain what the definitive explanation might be. Some explanations for the causes of the effect include:

• The power of suggestion
• Classical conditioning
• The doctor–patient relationship

Research into the placebo effect is always developing and throwing new light on the phenomenon.

Why are placebos used in research?

Placebos are used in medical research to help establish whether a trial treatment is effective. The placebo effect describes how even receiving a “dummy” treatment (e.g., a sugar pill or saline infusion) can lead to improvement in symptoms.

For this reason, researchers use a control group who receives the placebo and a treatment group who receive the experimental drug. The effectiveness of the new treatment is measured by how much better it is at treating the condition compared with the control group.

In most cases, researchers use a double-blind experimental design to reduce bias.