Motivational Effects that Defy 3: The Placebo Effect

This is the 3rd post in a series on motivational effects that concern expectations. In previous posts I looked at the Hawthorne effect and the Pygmalion effect. My interest in these was raised when I learned of them while searching for the possibility that people had looked into the Placebo effect in education.This time I would like to look at the Placebo effect, the one that originally got me interested in this trilogy.


So there I was, happily making my way through Ben Goldacre’s wonderful oughtta-read Bad Science, in which he is gleefully ripping into little shreds the reputations of detox artists, brain gym evangelists, homeopathic medicine promoters, and other quacks and hacks, when right in the middle of his book I come across a chapter on the placebo effect. In that chapter he takes us on a tour of this “fascinating, misunderstood… and counter-intuitive aspect of  human healing”. You can hear him sum up much of the chapter here in 5 minutes: sugar pills have effects, 4 sugar pills have more effect than 2, ‘brand’ placebo pills have more effect than generic ones, and a placebo injection or operation has more effect than a placebo pill because it is a more dramatic intervention. But there is more: what a doctor says and what a doctor believes when providing care can affect the outcome; and a placebo diagnosis of expectation of improvement can affect that improvement.

And the more people look for the placebo effect in the medical world, the more they find it; and the more they begin to look for the mechanism through brain imaging studies, etc., the more it begins to reveal itself. Here is a documentary showing some dramatic examples and some studies into the possible mechanisms at work. Fascinating stuff, but it’s time to make our segue back to the world of education.

One study that Goldacre recounts in his chapter  concerns a certain group of housekeepers at a hotel. They were divided into two groups and one group was told about the benefits of exercise and had pointed out to them the fact that they were sort of super-exercisers because of the line of work they were in. Four weeks later, both groups reported that they were doing the same amount of work (or “exercise!”), but the group that had received the information about the health benefits of their work now showed a decrease in weight and body fat, and an improvement in hip-to-waist ratio (Crum & Langer, 2007). This is mind-boggling. And it got me thinking about whether such Jedi mind tricks might be able to work in education. The beauty of Crum and Langer’s experiment is also sort of a stumbling block: they didn’t do anything beyond point something out. In an educational setting this would be difficult to replicate, since the teachers would be teaching, and the students would have lots of ways to adjust performance.

The closest thing I could find (and if you know of anything else, I’d love to hear about it) was an experiment on changing performance by changing mindsets. Blackwell, Trzesniewski and Dweck (2007) found that just informing junior high school students that the brain is like a muscle and that academic “exercise” can bring about improved academic ability got them to improve their academic performance. Even just a one-shot lecture by some university experts was enough to make a difference and make them believe in the “growth mindset”. Readers of the previous two posts in this series might now be wondering whether this experiment represents the Placebo effect, the Hawthorne effect, or the Pygmalion effect. To be honest, things are getting pretty blurry for me as well. We could argue that the researchers haven’t really done anything for the learners. That is, they haven’t made changes in the curriculum or run extra lessons with them. They have, however, pointed out an opportunity for improvement and–importantly–an expectation of success.  And they’ve definitely shown an interest in their improvement. I mean, the students would of course infer that these university researchers wouldn’t be there if they didn’t think they had something that would be effective, right? I think it might not be wrong to say that the same underlying mechanism–whatever that is–is at work in all these effects. Someone is watching you, someone is interested in your performance, someone believes you can do better.

Taking this idea further,  believing and higher expectations, coupled with a more rigorous curriculum can lead to significantly better performance. Anecdotal evidence suggests it can, anyway. Heath and Heath in their book Switch report on the success of a first grade language arts teacher in Atlanta who motivated her class and dramatically improved their performance on standardized tests by telling them that they would be reading like third graders by the end of the school year. That is, they were told and convinced that they would be not just  successful first graders,  and not even second graders, nope, they were going to advance to the level of third graders! And they did. At the end of the year, 90% of the class was reading at the 3rd grade level or higher. Perhaps we all need to push the envelope a little, while at the same time communicating our expectations of success. Certainly this is an idea worthy of more classroom research and larger-scale research.

I love the Placebo effect. I love the fact that it has been subjected to rigorous testing and found to hold true. The fact that it remains a little mysterious only adds to its charm. No doubt there are explanations for the phenomena and one day they will be widely known and appreciated, but for now it is enough to know of it and have some fun with it. It can be dangerous, too, for placebo side effects have been observed and the dangers of pigeon-holing learners must be acknowledged as well. But for teachers, deftly making use of our authority and making assertions that can lead to improvement is part of our job. Doctors don’t always understand why something gets better and teachers don’t always know how something gets learned. Understanding the Placebo effect and making it work for us is one of the things we can do. It comes with the position.

Sept. 2011 Update.

A recent Brain Science podcast interview with Fabrizio Benedetti looked at placebo effects. Dr. Ginger Campbell and Dr. Benedetti discussed what placebo effects (notice the ‘s’) are and are not, what other effects they can be confused with, and the mechanisms that are at work behind the effects. Here is a quote from episode:

  I would say that the take-home message for clinicians, for physicians, for all health
professionals is that their words, behaviors, attitudes are very important, and
move a lot of molecules in the patient’s brain. So, what they say, what they do in
routine clinical practice is very, very important, because the brain of the patient
changes sometimes. As you said, of course, there is a reduction in anxiety; but we
know that there is a real change. There is a real change in the patient’s brain
which is due to—in a single sentence, we can call it the ‘ritual of the therapeutic
The ritual of the therapeutic act is very complex. In the ritual of the therapeutic
act there is a doctor; in the ritual of the therapeutic act there are drugs, there are
syringes. Sometimes there are very complex machines, like an MRI machine, for
example. All these social and sensory stimuli constitute what we call the ‘ritual of
the therapeutic act;’ and the ritual of the therapeutic act communicates and tells
the patients that a therapy is being performed. And this is very important
because it induces expectation in the patient. So, absolutely, it is very, very
important for a clinician.

Audio, transcripts, references, and notes are available at the podcast’s website. Dr. Benedetti is the author of two books on this topic, Placebo Effects, and The Patient’s Brain.


March, 2013 Update.

A recent study described here in the Research Digest shows how a type of placebo–a bogus priming method–can result in better performance on quizzes. Researchers named Ulrich Weger and Stephen Loughnan got a group of mostly 20-yr-olds to believe they were being subliminally primed with test question answers before the questions appeared on the screen. In fact, nothing was shown, but that didn’t stop them from scoring significantly better than the control group. The researchers say this:

The placebo intervention “cannot have expanded the individual’s knowledge or storage capacities,” the researchers said. “What is more likely to have happened is a weakening of inhibitory mechanisms that normally impair performance on a task – for example, self-incapacitating anxieties that previously taxed cognitive resources.” The placebo might also have “primed a success orientation,” the researchers said, which may have affected the participants’ behaviour accordingly, including increasing their persistence.

The study was small and needs to be replicated, but this is indeed another strange and wonderful example of the placebo effect. The researchers plan to next investigate whether it can work without the participants  being fooled.


Crum, A., Langer, E. (2007). Mind-set matters: Exercise and the placebo effect. Psych Science 18, no. 2 (Feb). Pg 165-71.

Blackwell, L. A., Trzesniewski, K. H., & Dweck, C. S. (2007). Theories of intelligence and achievement across the junior high school transition: A longitudinal study and an intervention. Child Development, 78, 246-263.