The Placebo Effect: What Is it and How Does it Work?

The placebo effect explains why health and psychological improvements occur in people who receive treatment without an active ingredient. This phenomenon is highly influenced by two processes: conditioning and expectations.
The Placebo Effect: What Is it and How Does it Work?
Laura Ruiz Mitjana

Written and verified by la psicóloga Laura Ruiz Mitjana.

Last update: 02 April, 2021

Surely the concept of the placebo effect will sound familiar to you. We’re sure that you’ve heard about it or even experienced it yourself at some point. But do you really know what it is? What’s the difference between a placebo and a placebo effect?

How does this phenomenon work and in what way does it affect us on a psychological level? How can we explain its appearance? What can it be useful for? We’ll tell you everything you need to know in this article!

Placebo effect: what is it?

The placebo effect is normal for pain.
Placebos are often used in the treatment of pain.

Placebo is defined as a substance that lacks curative action but produces a therapeutic effect on the person. We often speak of the placebo effect as a consequence of taking this substance.

Thus, the person who takes it believes that it’s an effective drug, and therefore improves thanks to that belief. However, the improvement isn’t due to the drug itself, which has had no effect on your body.

In medicine, the placebo is usually a pill with the same appearance, taste, and shape as a “real” medicine, but which is made from inert products and without any active ingredient.

Another definition for the placebo effect would be the one proposed by Dr. Rosa María Lam in a 2014 article. According to her, a placebo is called an “intervention designed to simulate a medical therapy, but which doesn’t have specific effects for the condition being applied.”

As we will see, suggestion and expectations play an important role in the placebo effect.

Expectations for improvement

However, the placebo effect doesn’t only have to do with substances, but also with complete therapies. For example, in psychology, we speak of treatments (as well as substances) that don’t have the qualities to produce an improvement in the patient’s symptoms.

Thus, improvement occurs due to other factors, such as suggestion and expectations, but not due to the characteristics of the treatment or substance itself.

The fact that the person feels that they’re receiving a treatment, causes them to believe that they will improve, and this belief is what makes them improve. In other words: the placebo effect is produced by the positive expectations we place on some substance or treatment, which we believe will do us good.

This arises because we’ve been informed of its curative effects, or because we believe or think that it’s going to help us. That is, we’re influenced by a certain belief or idea.

An example of the placebo effect

A typical example of a placebo effect would be when we have a headache. We take a pill that they tell us is an aspirin (when in reality it’s just “sugar”, that is, it has no active ingredient). As a result of taking it, the headache disappears.

This would be an example that shows that there are illnesses where suggestion plays a key role; in the case of a headache, the person, by relaxing and relying on the pill, may feel the pain subsiding. This is the placebo effect.

How does the placebo effect work?

But how can we explain, on a psychological level, how the placebo effect actually works? The explanation lies in two basic mechanisms: conditioning and expectations, which we’ve already mentioned.

Conditioning is a type of learning through which two events are associated. In this case, the treatment is associated with the idea of improvement (also through expectations).

In this way, when a person receives a placebo treatment (without them knowing that it is a placebo) the positive expectation arises that they will recover or improve.

This is so because, throughout that person’s life, they have learned that, generally, an improvement occurs after receiving a certain treatment. This is what expectations consist of, which are defined as the hope or possibility of achieving something.

Expectations and conditioning

Well, these expectations would condition our response to treatment. How? By favoring our recovery response and improvement.

Thus, in a generic way, the greater the expectation of improvement, the greater the placebo effect (this causes the conditioning to be greater and greater). Of course, it’s necessary that the initial expectation occurs, in order for the placebo phenomenon to take place.

What else influences the placebo effect?

We can say that expectations and conditioning are the factors that most influence the placebo effect. However, they aren’t the only variables that influence this psychological phenomenon. In this sense, we also find:

  • The professionalism projected by the person who administers the treatment.
  • The sense of competence that their professional reflects.
  • The context in which the treatment is carried out.
  • The kind of problem we are facing.
  • The cost, presentation, materials, or rituals involved in carrying out the treatment.

In general, placebos with a more expensive and more elaborate appearance tend to be more effective (that is, their placebo effect is more powerful). To better understand this, let’s take a simple example. A sugar pill is more effective in producing the placebo effect if it’s in the form of a capsule, than if it’s in the form of a lump.

In this example, the appearance of “uniqueness” would raise our expectations about the effectiveness of that treatment, substance, or pill.

What happens at a neurological level?

The placebo effect is related to drugs.
In studies that require a placebo, the patient never knows if they’re receiving the true treatment.

According to studies, and more specifically a study by Oken (2008), at a neurophysiological level, a series of brain changes occurs in the person who experiences the placebo effect.

In this sense, it has been shown that the application of the placebo stimulates the following structures: the frontal cortex, the nucleus accumbens, the gray matter, and the amygdala, which activates the dopaminergic and serotonergic pathways (especially the dopaminergic ones).

Basic mental processes

Having said that, the placebo effect’s mechanism of action still isn’t completely clear. It seems to be a process in which abstract thinking influences very basic and primitive mental processes. Very similar processes are present both in humans and animals.

What is it useful for?

The placebo effect has been shown to be useful or effective in relieving, above all, pain symptoms. It has also made it possible to improve somatic symptoms, Parkinson’s disease, dementia, and epilepsy.

In the case of pain, the effects have been observed to be very intense or powerful in those who had a preponderant initial pain.

One concept that we can relate to the placebo effect is the Pygmalion effect (also called self-fulfilling prophecy). This phenomenon is based on something happening as a result of having the expectation it will happen.

Through the Pygmalion effect, the person has a certain belief, and, as a result of it, they unconsciously end up directing all their actions and attitudes towards that goal. This is what would make it happen.

As we can see, it resembles the placebo effect in its mechanism: there are certain expectations that something will happen, and that something ends up being fulfilled (which confirms our initial expectations or hypotheses).

The other side of the coin: the nocebo effect

The nocebo effect would be the other “side of the coin” of the placebo effect. In this case, we’re talking about suffering a worsening or a negative side effect due to the application of a placebo treatment.

The negative consequences of such treatment, or the worsening suffered by the patient, aren’t explained by the treatment itself, but by the belief that the treatment will harm us in some way. That is, the mechanism is the same as in the placebo, except that here we’re talking about a worsening (harmful effects, hence the name of the term) and not an improvement.

Research into the nocebo effect

Research into the nocebo effect is less extensive, although we do know that expectations also play an important role in it (in this case, to worsen the condition).

In addition, it should be mentioned here that the investigation of this phenomenon is rather complicated, as it entails a series of ethical dilemmas. That’s why experts often choose to study it indirectly.

The placebo effect exists and has been demonstrated in numerous investigations (although its explanatory mechanism still holds some mysteries). It’s a psychological mechanism that can help people feel better or even to recover from symptoms.

Of course, we have to be careful, because the placebo effect could never explain the cure of a biological disease. However, on a psychological level, it does make more sense. In any case, more research is needed in order to continue delving into this phenomenon, its power, and how we can benefit from it.

“Hope, in its vigorous sense, means confident faith in the goodness of nature, while expectation, as I’ll use it here, means trusting in results that are planned and controlled by man.”

-Ivan Illich-

  • Finniss, D.G.; Kaptchuk, T.J.; Miller. F. & Benedetti, F. (2010). Placebo effects: biological, clinical and ethical advances. Lancet, 375(9715):686-695.
  • Grelotti, D.J & Kaptchuk, T.J. (2011). Placebo by proxy. British Medical Journal.
  • Lam, R.M. y Hernández, P. (2014). El placebo y el efecto placebo. Revista Cubana de Hematol, Inmunol y Hemoter, (3):214-222.
  • Oken, B.S. (2008). Placebo effects: clinical aspects and neurobiology. Brain.; 131(11): 2812–2823.
  • Sanchis, J. (2012). El placebo y el efecto placebo. Medicina Respiratoria; 5(1):37-46.

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