The placebo effect refers to any situation where body and
mind are affected by an intervention to a greater degree than would be expected
based on the intervention itself. Most
commonly, we think of placebos as pills or shots that have no active medical
ingredients in them that lead to improvements in health. Placebo effects are incredibly powerful.
A fascinating paper by Baba Shiv, Ziv Carmon, and Dan Ariely
in the November, 2005 issue of the Journal
of Consumer Research explored how placebo effects are influenced by what
people know about the placebo.
In a series of studies, these researchers had people drink
an energy drink that was advertised as affecting people’s mental ability. To determine the effect of the drink on
people’s performance, they measured the number of words that people were able
to unscramble. The key aspect of the
study focused on the information that people were given about the drink.
In one study, people were told about the effectiveness of
the brand SoBe, which is a real product.
One group was told that a large number of studies suggest that drinks
like this create large improvements in mental functioning. A second group was told that the drinks
provide a slight improvement in thinking.
Participants were also told about the cost of the drink. Half of the participants were told that the
drink cost its regular price ($1.89), while a second group was told that it was
purchased at a discount ($0.89).
Finally, a control group performed the word-unscrambling test without
hearing about the drink at all.
The control group got about 7 problems correct. Those people who read that the drink was not
that effective generally did worse than the control group, while those who read
that the drink is highly effective did better than the control. The price of the drink also affected
performance. Those who got the
discounted drink also performed worse overall than those who got the full-price
drink. Indeed, the people who got the worst
combination of information (the drink is only slightly effective and was
low-priced) got only about 4 problems correct, while those who got the best
combination of information (the drink is highly effective and regularly priced)
got over 10 problems correct.
As part of the study, people were asked to rate how
effective they thought the drink would be at influencing their thinking
ability. These ratings were a good
predictor of people’s performance. That
is, the more that people believed in the drink, the more that it had an effect
on the number of problems they solved.
These results are quite important for thinking about placebo
effects. You might think that you get
placebo effects just from being a part of an intervention. For example, you may learn that taking a pill
makes you feel better, and so your body may react in ways that make you feel
better whenever you take a pill.
Ultimately, then, part of the effect of a placebo
is based on how much you believe in it.
All of the factors that determine whether you think something will work
as promised can influence placebo effects.
That is why price affects the placebo effect. We normally think of discount products as
being less effective than full-price products.
That same belief also influences the influence that a placebo has on us.
