A placebo is an ineffective treatment given in a controlled study as a
In one of the first large scale double blind tests done in medicine, the test
of the Salk Polio vaccine, half the test subject children were given
injections of the Salk vaccine and the other half were given sterile
injectable saline, a salt solution with the same percentage of salt as normal
body fluids. Because the Salk vaccine was slightly pink, the placebo saline
was tinted pink. That is the placebo was a treatment that looked like the
real thing, but when injected would have no effect at all. The test was
evaluated by comparing the reduction in polio cases in the group receiving the
Salk vaccine to the group receiving saline. What could be simpler than
comparing something that might work with something that doesn't work. No one
had to explain this procedure more than once to the elementary school children
who were the test subjects.
But an adult may ask why use the placebo at all? If it does nothing why not
just compare the test group with the historical rate of polio cases? The
problem is the historical rate of polio varied a lot. No one could prove why
the rate changed, but they knew it did. In some summers there were far more
cases than in other years. The placebo was used so the groups of children
were tested in the same season under all the same conditions. Whatever the
conditions enhancing or inhibiting polio in some years were, they would at
least be the same for both test groups.
Why inject the children with pink saline? Why not just make a list of the
untreated children's names? This is the interesting question! In this kind
of test, it has been found that both test groups do better than would be
expected. This seems to be because if a doctor treats someone they tend to
feel better, whether the doctor gives any medicine or not.
No one knows why this is true, although there is a lot of speculation. The
point is that it does happen and to test a new drug, it has to be eliminated
to be sure the test results are real.
In summary placebos are used because it is normal for people to feel better
when treated by a healer whether or not the healer gives effective medicine or
snake oil. This fact of feeling better when treated with or without an
effective treatment is called the placebo effect. That is the placebo effect
is the fact that people feel better even when given a treatment that does
No one knows why this is true, but we have proof that it happens. I emphasize
this because critics often try to respond to the many theories of what might
cause the placebo effect. We don't know what causes it, but we do have solid
proof that it does happen.
In comparing audio components the same thing happens. A new component will
usually sound different from the old component. This holds true even when the
component is identical, as when a trick comparison is done of one component
with itself. Here too, no one knows why it happens, but there is proof that it
Just as the placebo effect is removed from a drug test by a double blind
procedure, we can remove it from an audio comparison by preventing the
listener from knowing which component is which.
|With this control, it becomes much harder for the listener to tell which
component he is listening to. But if he hears a difference, we can be sure it
is a real difference, not an auditory placebo effect.
Audiophiles are often shocked and offended by how much change there is in
their "ability" to hear sonic differences when a comparison is done with a
double blind protocol. They try to blame the slightest detail of the test
equipment or procedure rather than realize that the blind test result is
reliable and their previous experiences were tainted by the placebo effect.
In conclusion, in any audio comparison look out for the placebo effect. Who
wants to spend money for a new component because it sounds better only to find out
later that there is no difference in the sound quality? If you are buying a
new audio component you want to be sure you are getting a worthwhile change not
just a warm feeling from the newness of it. Of course if you like to spend
money and feel good about it, you have the right to do that. The results of
careful double blind comparisons are for those who want the best, but have
less than infinite funds, and like to get value for their money, along with
those who are interested in understanding the nature of human responses.