One of the main advantages of using a placebo in medical and psychological studies allows researchers to eliminate or minimize the effect that expectations have on the results. If researchers hope to find a certain result, they may unknowingly pass on clues, known as demand characteristics, that could lead participants to guess what the researchers hope to find. As a result, the behaviors of the participants can sometimes change.

To minimize this, researchers sometimes conduct what is known as a double-blind study. Such studies imply that both experimenters and participants are unaware of who is receiving the real treatment and who is receiving the sham treatment. By minimizing the risk of subtle biases influencing the study, researchers can better observe the effects of both the drug and the placebo.

The Placebo Effect in Psychology Experiments

In a psychology experiment, a placebo is an inert treatment or a substance that has no known effects. Researchers can use a placebo control group, which is a group of participants who are exposed to placebo or a sham independent variable.  The impact of this placebo treatment is compared with the results of the actual independent variable of interest in the experimental group.

Although placebos do not contain an actual treatment, researchers have found that they can have a variety of physical and psychological effects. Participants in placebo groups have shown changes in heart rate, blood pressure, anxiety levels, perception of pain, fatigue, and even brain activity. These effects point to the brain’s role in health and well-being .

While researchers know that the placebo effect works, they do not yet fully understand how and why this effect occurs. It is being investigated why some people experience changes even when they are only receiving a placebo. Several different factors can contribute to the explanations of this phenomenon , below we will answer this.

Placebos can trigger hormonal responses

One possible explanation is that taking the placebo can trigger an endorphin release. Endorphins are similar in structure to morphine and other opioid pain relievers and act as the brain’s natural pain relievers. The effect of placebo in action is similar to opioids, known using brain scans, showing that areas containing many opiate receptors are activated in both the placebo and treatment groups. 

Naloxone is an opioid antagonist that blocks both natural endorphins and opioid medications. Using naloxone, pain relief with placebo is reduced.

Expectations can influence placebo responses

Other possible explanations include conditioning, motivation, and possible expectations. In some cases, a placebo can be combined with a real treatment until it tries to evoke the desired effect, an example of classical conditioning. People who are highly motivated to believe that a treatment will work, or who had a previous treatment, may be more likely to experience a placebo effect .

The enthusiasm of a prescribing physician for a treatment can even affect the patient’s response. If a doctor seems very positive that a treatment will have a desirable effect, a patient is more likely to see the benefits of taking the drug. This shows that the placebo effect can take place even when a patient is taking real drugs to treat a disease.

Placebos can also cause side effects

Conversely, individuals may experience negative symptoms in response to a placebo, a response sometimes known as the ” nocebo effect .” For example, a patient may report headaches, nausea, or dizziness in response to a placebo.