研究の中でプラシーボ

Placebos are widely included in clinical research and play an important role in therapeutic interventions. While clinical research relies on the efficacy of therapeutics for treating many disorders and illnesses, participants often have preexisting thoughts that can influence the outcome of drug trials. Such beliefs are referred to as placebo effects. The placebo effect points to the importance of perception and a psychological role in physical health. For example, the recent rise in the popularity of yoga as a fitness routine in Western countries has led to widespread beliefs regarding its benefits on health and wellness, including the idea that yoga enhances creativity. Through a unique experimental design, this video demonstrates how to design, perform, analyze, and interpret placebo responses. Here, the study examines whether a participant’s beliefs that yoga enhances creativity influences their creativity by listing alternative uses for a clothespin after stretching.

This placebo experiment incorporates a two-group design, a placebo and stretching group. In this case, the experiment is designed to highlight the placebo effect and should not be considered a control group, as it would be in other experiments. The two groups undergo the same series of stretching exercises. The placebo group is led to believe that they are going to engage in a series of yoga movements, whereas, the stretching group is led to believe that stretching is a critical component to personal fitness, with no mention of yoga. Note: the only difference is in the instructions given to the participant and no actual yoga is performed. After stretching, the participants are asked to list alternative uses for a clothespin. This dependent measure is interpreted as creativity. Participants who believe that doing Yoga leads to enhanced creativity should display a stronger placebo response than those who do not.

To setup the experiment, you will need: informed consent paperwork, copies of the initial research description and goals, a blank, lined piece of paper, writing pen, a clothespin, and copies of the final nature of the study for debriefing. To begin the experiment, meet the participant in the lab and explain the experimental guidelines. Guide all participants through the consent process, brief them with a description of the research on yoga and creativity, and discuss the overall plan for the session, including the potential risks and benefits. Assign this participant to the placebo yoga condition. Influence the participant that he or she is about to engage in a series of yoga movements. Remember that participants are not doing actual yoga movements, just stretching. Once the participant has been persuaded with the intent of yoga, direct him or her to do several “yoga” stretches and hold them for 1 min. Let the participant know that he or she can withdrawal at any time and ask for help if they experience discomfort. While the other participant is stretching, bring a different subject into the laboratory and assign them to the other experimental group, the stretching condition. After the participant has consented to the experiment, convey the message that the benefits of stretching are being tested. Now instruct the participant do several stretches and hold them for 1 min. Note that these are purposefully the same stretches as in the placebo condition. In a different room immediately after the stretching exercises, give participants a piece of paper with numbered lines and a pen. Ask the participant to list as many possible uses as you can think of in the next 3 min for a clothespin. Once the 3 min task is finished, ask the participant about their perception of yoga as it relates to physical and mental benefits including creativity and open-mindedness. At the conclusion of the experiment, debrief participants and explain why deception was necessary for the experiment.

The analysis of creativity after “yoga” stretching involves counting the number of ways participants listed to use clothespins. The data are then graphed by plotting the mean numbers for each condition to compare the placebo “belief in yoga” condition against the stretching condition. In this experiment, the placebo group listed more ways to creatively use clothespins than the stretching group.

Now that you have seen an experiment designed to uncover the extent of a placebo effect, let’s take a look at how researchers include placebo groups as important controls to study the effectiveness of medications. For example, in pharmacotherapy studies, subjects are unknowingly given a sugar pill—the placebo—and an active pill—the drug—and take them in random order. In many cases, medications are effective and produce beneficial effects on the measured outcome, as in this example where motor function was restored in patients with spinal cord injury after the administration of an anti-depressant drug compared to the placebo pill.

You’ve just watched JoVE’s introduction to placebos in research. Now you should have a good understanding of how to design and perform the experiment, as well as analyze results and apply the phenomenon. Thanks for watching!