The Placebo Effect

What You Need


  • Newsprint and markers
The Placebo Effect


To learn about the placebo effect—what it is, what it has taught researchers about brain function, and why it is important for people to understand its potential impact on their lives.


During this lesson, students will learn more about the placebo effect. They will investigate several research projects, designed to study different medications or behaviors, which illustrate how the placebo effect works. Then they will apply what they have learned to a scenario involving a clinical trial and the use of placebos.

During clinical trials, researchers typically divide participants into two groups—the experimental group and the control group. The experimental group receives the product being tested, while the control group receives a placebo, a physically inert substance identical in appearance to an active pharmacological medical treatment being investigated. Occasionally, active substances are used as placebos. These active placebos have side effects that mimic those of the drug being investigated but do not possess the physical properties hypothesized to produce the beneficial treatment effect.

This process illustrates scientific inquiry. Placebos are used so that the medical treatment being tested can be compared to another substance. The two groups being tested are virtually identical, which ensures that the test is valid. In such tests, the working hypothesis is that the treatment group will improve and the placebo group will not. 

For several decades, researchers have noticed that even though placebos have no active agents, they often make people feel better. In many clinical trials, people in the control group report feeling better as soon as they start taking the placebo. This reaction, induced by the simple act of taking a medication that a person thinks will make him or her better, is known as the placebo effect. This discovery illustrates the power of scientific inquiry and how it can expand our scientific knowledge and understanding.

After learning the basic definition of the placebo effect, students then find out about some of the studies that have been done on this topic. For example, researchers at the University of California at Los Angeles (UCLA) conducted a double-blind study of 51 patients with depression. (Double-blind means that neither the researchers nor the patients knew who was receiving the medication and who was receiving the placebo.) Not only did 38% of the patients taking the placebo report feeling better (compared with 52% of the patients taking the anti-depressants), but brain waves showed a significant increase in activity. This finding illustrates that there is a chemical change in the brain as a result of the placebo effect (“Power of Placebos,” News 8 Austin, January 13, 2003 ).

After completing their research and recording their findings, students then refer to a scenario that involves a clinical trial and the use of placebos. Using what they have learned about the placebo effect, students will respond to the dilemma posed in the scenario. Questions are given to help students clarify their thinking. By the end of the lesson, students should have an understanding of why the placebo effect is significant and why it is important to be aware of its impact on the human brain.

Ideas in this lesson are also related to concepts found in the following National Science Education Standards:

  • Science as Inquiry: Understandings about Scientific Inquiry (9-12) #2, 6
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Begin the lesson by having students use their The Placebo Effect student esheet to listen to Hotel Maids Challenge the Placebo Effect from the National Public Radio. As they listen to the story, they should answer the questions on their Understanding the Placebo Effect student sheet.

This show recounts how Harvard researcher Ellen Langer explored the perceptions that hotel maids had of their bodies. Although the women got a considerable amount of exercise through their work, 67% reported that they didn’t exercise, and more than one third of that group said that they didn’t exercise at all. In addition, based on simple measurements, such as blood pressure, weight, and waist-to-hip ratio, most of the women did not appear to be physically fit.

Langer hypothesized that the reason the women didn’t appear physically fit was that they didn’t think of themselves as such. The goal of Langer’s study was to change their perceptions. She divided the maids into two groups of 84. With one group, the researchers went through the women’s routine, explaining how many calories were burned with each task they performed. The other group received no information. One month later, Langer and her team took physical measurements of the women and found that the group that had been educated showed a decrease in blood pressure, weight, and waist-to-hip ratio. Langer interpreted these findings to mean that if the women believed that they were exercising, then their bodies responded as such. In other words, Langer believes that the placebo effect resulted in these real changes in their bodies. Although other researchers disagree with her interpretation, the study nonetheless raises intriguing questions about the power of the placebo effect (Alix Spiegel, “Hotel Maids Challenge the Placebo Effect,” National Public Radio, January 3, 2008).

Discuss the story with your class, using these questions as a guide:

  • What is the story about?
      (The story is about how the maids’ perception of themselves affected typical measures used to assess physical fitness. Even though the maids exercised regularly, they did not perceive themselves as physically fit, and simple measurements, such as blood pressure, weight, and waist-to-hip ratio, matched that perception. During the experiment, the researcher, Ellen Langer, divided the 84 maids into two groups. With one group, the researchers went through the women’s routine, explaining how many calories were burned with each task they performed. The other group received no information. One month later, Langer and her team took physical measurements of the women and found that the group that had been educated showed a decrease in blood pressure, weight, and waist-to-hip ratio.)
  • What do you think this experiment illustrates?
      (Answers will vary.)
  • How do you think the researchers interpreted these findings?
      (Langer interpreted these findings to mean that if the women believed that they were exercising, then their bodies responded as such.)

Then ask students if they have ever heard of “the placebo effect.” If so, ask them what they know about it. Write down their ideas on a sheet of newsprint. If students have never heard of the placebo effect, guide their thinking by asking these questions:

  • Do you ever feel better right after taking medicine, before the treatment would have had time to work?
  • Have you ever heard people talk about “sugar pills”? Do you know what they were referring to?
  • Have you ever felt better or worse just by thinking about something?

After discussing these questions, work together as a class to arrive at a definition of the placebo effect. A sample definition follows:

    The relief that people get from the anticipation of treatment, even if the treatment turns out to be nothing more than a sugar pill. Alternatively, the changes in the brain and the body that can occur as a result of a change in perception about a situation.

Ask students to apply this definition to the story about the maids. Help them understand that because the experimental group now believed that they were physically fit, their bodies responded accordingly.


Have students continue their study of the placebo effect by using their student esheet to go to and read Your Health: The Placebo Effect. This selection has an explanation of the placebo effect. Discuss this selection with the class.

Ask students to learn more about the placebo effect by checking out the websites listed on their student esheet. Students should use the chart on the Understanding the Placebo Effect student sheet to write down the key points highlighted in each site.

Then ask students to have the Applying the Placebo Effect to a Real-life Scenario student sheet available. Have them read the scenario that is presented there. For your information, it is shown here as well.

What Should the Allens Do?

      Mr. and Mrs. Allen were faced with a difficult situation. Her husband was in the early stages of pancreatic cancer. Although he could still drive and cook—his lifelong passion—he was getting weaker by the day. Each day, he spent more time in his recliner, watching television and dozing.
      The Allens’ oncologist told them about a clinical trial that Mr. Allen would be eligible for. The only problem was that it was a double-blind study, meaning that no one, including the Allens and the researchers, would know whether Mr. Allen was receiving the placebo or the medication being investigated. Mrs. Allen was afraid that they could lose valuable time if her husband signed up for the clinical trial and then received the placebo. His condition could worsen. But if he received the medication, he could improve. She kept weighing the pros and cons, uncertain what to do.

After reading the scenario, have students pick a partner. Ask each pair to write a recommendation for Mrs. Allen. Students can use these questions to guide their thinking:

  • What issues, in addition to the ones mentioned in the scenario, do you think the Allens need to consider?
      (The Allens need to be aware of the placebo effect, which could play a role in the way Mr. Allen responds to the clinical trial. There is a possibility that even if he receives the placebo, his condition could improve because of the impact of the placebo effect.)
  • Do you think the Allens should ask for additional information before making a decision?
      (Yes, they might consider requesting that Mr. Allen have a full-body CAT scan before the trial begins and then during the trial. The CAT scan would give everyone information about how the trial was progressing, including whether there were any signs of the placebo effect.)
  • Based on what you know about Mr. Allen’s situation, as well as the placebo effect, what would you recommend that he and his wife do?
      (Answers will vary.)


To help you assess student understanding, hold a class discussion using questions like these:

  • What is the difference between a placebo and the placebo effect?
      (A placebo is a substance, such as a sugar pill, that is given to a group of individuals instead of an actual medication. The placebo effect is the impact on an individual of having received a placebo. The impact is often positive.)
  • Under what conditions has the placebo effect been observed?
      (The placebo effect is often observed during clinical trials, when the control group, which has been receiving the placebo, shows signs of improvement. The placebo effect also has been noted when people say they feel better right after taking an aspirin, before it has had time to work.)
  • Describe one study that has documented the placebo effect.
      (An important study documenting the placebo effect was one done with depression patients at UCLA. The group receiving the placebo showed almost as much improvement as the group receiving the anti-depressant.)
  • What part of the brain is involved in causing the placebo effect?
      (Studies have shown that the prefrontal cortex becomes activated when anticipating a reduction of pain. The anticipation results in a reduction of activity in pain-sensing regions of the brain. There is also a possibility that the actions of the prefrontal cortex trigger a release of opioids in the midbrain, which also have a pain-relieving effect.)
  • How is new technology used to study the brain, such as the MRI, changing the way researchers view the placebo effect?
      (By using MRIs and other forms of technology, researchers can see what is happening inside the brain and body when a placebo is administered. The fact that activity in the brain has been detected is adding to the growing body of evidence proving the existence of the placebo effect.)

If you find that you want to follow up these assessment questions with some other activity, you could have students do some of the activities suggested in the Extensions.


Ask students to consider a series of scenarios of actual medical studies and/or the data from them and ask students to determine the answers to such questions as: 1) whether the placebo effect is possible in this study; 2) if so, does it seem to occur or not; 3) if so, to what degree does it seem to do so? Students can go to MedLinePlus as a starting point for their studies.

Have students write about the placebo effect. Their essays should demonstrate knowledge of what a placebo is, how it is used, and what the placebo effect is. Make sure students cite sources used in this lesson in their answers.

Ask students to consider this question/statement: “The placebo effect relies on deception.” Then ask students to explain it. Do students think it would be ethical to use placebos in the treatment of patients? Why or why not?”

Suggest that students check out these websites to learn more about the placebo effect and the controversy that continues to surround it:

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Lesson Details

Grades Themes Project 2061 Benchmarks National Science Standards