Suggestion and Perception
A long time ago, at a lake cabin in New Hampshire, a friend of my
parents (call him John) was talking to his daughter's boyfriend about
beer. The boyfriend couldn't understand why John would drink Carling
beer when Schaefer was obviously superior. John poured beer into two
glasses while the boyfriend wasn't looking and asked him if he could
tell which one was which. The boyfriend tried them both and clearly
expressed his preference for the one he assumed was Schaefer. It turns
out both were the same beer (I don't recall
which one). Something peculiar was happening here. It seems that the
boyfriend's perception of taste was influenced not just by taste, but
by his expectation that the two beers were different.
A few years ago we had some friends at our house to try tasting
different foods and drinks. One of them was vanilla ice cream. We had
three brands: Haagen-Dazs, Kemps (a moderately priced brand popular in
Minnesota) and an inexpensive store brand. Our guests weren't told
which was which. Most of them clearly preferred both the Kemps and the
store brand to the Haagen-Dazs. They were surprised since they had
initially assumed that the Haagen-Dazs was better since it is quite
expensive, has a high cream content, and has a top-notch reputation.
Since most people try many brands of ice cream over their lives, we are
likely to assume that the reputation of a "premium" ice cream like
Haagen-Dazs is the result of it actually tasting better. In fact it may
be that there is an illusion of tasting better caused by expectations.
It turns out that in blind tests, where expectations cannot influence
the perceptions, the results are often unexpected.
When we form a judgment about something we have experienced ourselves,
like how much we like a beer or ice cream, we naturally assume our
judgment is based entirely on our own perception. However if we have a
prior expectation based on what someone has told us or something we
have assumed, that expectation may have a strong influence on our
opinion that we don't recognize. This is sometimes called the "power of
suggestion". It can lead us to false beliefs because we think we have
determined something for ourselves when in fact we are just passing on
a (possibly erroneous) impression we got elsewhere.
A common situation where perception is distorted by expectations is
when people judge value on the basis of price. A friend told me a story
of a shopkeeper who had some knick-knacks that had been priced at two
dollars. Nobody bought them. On a whim he raised the price to five
dollars. To his surprise they sold out quickly. Apparently buyers
assumed that the higher price implied better quality. While it is
certainly true that higher priced items have the potential to have
higher quality, it is also possible that high prices are due to
advertising costs, ingredients that are costlier but no better, or
simply increased mark-up.
A number of years ago the concept of "pyramid power" became popular. It
involved the belief that pyramid shaped structures somehow focused
power in a way that was beneficial to things inside them. One of the
claims was that razor blades would stay sharper if stored in a pyramid
shaped container between uses. People who tried this were quite
confident that it worked, but their
judgment was made with full knowledge of whether the blades they were
using had been stored in the pyramid. When testing was done without the
possibility of bias, the effect disappeared. While it is relatively
harmless if we make mistaken judgments about the taste of ice cream or
beer, the pyramid case can be troublesome because it could lead people
to mistakenly believe in a miraculous effect that would invalidate
important principles of science. If taken seriously, scientists could
waste a lot of time and money trying to develop a scientific theory
about an effect that did not exist.
This type of problem is well known in science as the "placebo" effect,
and it often makes doing scientific experiments considerably more
difficult. Imagine that a new pain killing drug is being tested. If the
patients who are given the drug are expecting it to benefit them, they
are likely to report a benefit even if the drug is ineffective. It may
be that they actually feel better just because they know they are
getting some sort of treatment, or it may be that, believing the drug
to be effective, they assume they would have felt worse without it. To
prevent getting erroneous results because of this effect, experiments
are usually designed so that patients do not know whether they are
getting a real treatment or a fake treatment (known as a placebo). If
the fake treatment is just as helpful as the real one, then it is
likely that any benefit reported from the real one is just caused by
the placebo effect and not the drug.
A dramatic case of suggestion influencing perception occurs with a
phenomenon known as "facilitated communication" which involves children
with autism. Martin Gardner
(2001)provided the
following description of how it works (Gardner uses masculine pronouns
for the child since most autistic children are male):
An
autistic child is seated at a typewriter or computer keyboard, or
perhaps
just a sheet of paper with the keyboard drawn on it… A
therapist, usually a
woman, is called the child's "facilitator." She asks the child a
question, then grasps his wrist, or elbow - usually the hand - while
the child
extends his index finger and begins to type. The belief is that the
child has
the ability to communicate intelligent thoughts by typing, but lacks
the
muscular coordination needed for finding the right keys. The
facilitator assists
him in locating the keys she is sure he intends to hit.
A wondrous miracle now seems to take place. Although the child has been
thought to be
mentally retarded, unable to read, write, or speak coherently, he types
out lucid, sophisticated messages that could only come from a normal
intelligent mind.
The children were apparently able to answer questions, identify
pictures, and tell about their feelings. Facilitated communication was
adopted in many treatment centers around the world and described in
newspapers and magazines including Readers Digest. Some people,
however, recognized serious problems with the method, such as the fact
that the child often was not looking at the keyboard when he chose the
keys. Eventually some tests were done where the child was asked a
question using earphones so the facilitator could not hear what was
said, and sure enough, the answers were unrelated to the questions. In
another test the child was shown a picture and the facilitator was
shown a different picture but led to believe it was the same one the
child saw. The typing represented what the facilitator saw rather than
what the child saw. Clearly facilitated communication did not really
work to communicate the child's thoughts, but instead communicated the
facilitator's expectations.
How does this related to things like beer tasting and placebos? It is
widely agreed that the facilitators were sincere people who were not
deliberately faking the results. Their choice of keys was based on
their own expectations of what the child might want to say rather than
their actual perception of the child's movements. So, like people
tasting foods or taking placebos, their perceptions were misled by
their expectations.
The problem presented by facilitated communication was particularly
serious because some of the messages wrongly believed to have come from
the autistic children involved accusations of sexual abuse. Dozens of
men were arrested based on this fallacious "testimony", and some spent
jail time before it was recognized that the information was totally
invalid.
An interesting case of mistaken perception was described by Phil Klass,
an investigator of UFO claims:
At approximately 8:45 P.M. CST on the night of
March 3, 1968, three well educated adults, standing outside near
Nashville, Tennessee, saw what they later described as a giant,
saucer-shaped, metallic craft with many square-shaped windows
illuminated from inside the craft, headed
out of the sourthwest toward the northeast. It passed overhead silently
at an altitude estimated at only one thousand feet.
The U.S. Air Force also received a UFO sighting report
from six persons living near Shoals, Indiana, some two hundred miles
north of Nashville, who said they had seen the same object, which was
described as being
cigar shaped, with numerous square windows illuminated from inside, and
with a rocketlike exhaust emitted from the rear of the craft. (Klass,
1981)
It turns out this object was the reentry of a Russian rocket booster
that
had been used to launch the Soviet Zond 4 spacecraft.
Why did people describe it as having an oblong or saucer shape, the
windows as square, and only a thousand feet up when it was actually
high in the sky hundreds of miles away? Probably because human
perception tries to match what is seen with known objects. In this
case, an airliner seen in the dark with lit windows would have looked
similar to the
row of bright rocket fragments, so they probably used this as a
starting point for their
judgments about the object. An airliner would be expected to have
square windows, and judgment of its distance would be based on the
spacing of the "windows" from each other. Their minds would have filled
in the details, and since the whole sighting took place in the span of
just a few seconds, there was no opportunity for more thoughtful
examination. The end result is that reliable people, attempting to be
perfectly honest, tell a false story. This is a quite normal type of
human error, and could happen to any of us.
Normally when we are confident someone is honest and
they tell us that they have learned something through direct personal
experience, we feel it must be true. This applies even more so when we
feel we ourselves have learned something from our own experience.
Hopefully the above examples show that even though people are honest,
sane, and perfectly intelligent, they can still have experiences and
perceptions that are wrong. It is important to take this into account
when we are trying to determine what is true.
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