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My reaction to the question about polygraphs is somewhat similar to that of
Amanda, though not as strong.  I am a psychologist and my main question
about the exhibit is what exactly you want to convey with it.  It seems to
me that the reality about polygraphs is probably too subtle to convey easily
in this form, and my main concern would be that the end result could easily
be a misrepresentation or science "lessons" that are counterfactual or
counterproductive.

The polygraph itself is based on solid psychological principles in the sense
that the measures it assesses are legitimately physiological responses that
occur in the context of arousal and are used in a lot of psychological
research.  The main problem I have with the polygraph is the inference made
that what one is measuring is necessarily "lying" and that it can be
accurately measured.  What you are measuring is a set of physiological
responses, but these responses don't reliably correlate the truth or falsity
of the person's statements, at least not to the extent that we call it a
"good" measure of lying.  There are more factors (a range of emotions, for
example) that impact these physiological measures in addition to lying, and
in this case you could end up with a false positive.  There are some
conditions and some people who don't have the common physiological response
to lying, so the test would produce a false negative.  The polygraph itself
is not reliable enough to be admissible in court as a measure of veracity,
and I think this is consistent with the evidence.

Interestingly, the extent to which the polygraph is accurate depends on how
much the person being tested BELIEVES that the polygraph can detect lies.
If a person believes that it works, they are more likely to have the
physiological response that is supposed to be the "typical" response for
liars.  So paradoxically, if a science museum is convincing the public that
the polygraph "works" to detect lies, the effect is to make it more accurate
for the public!  For the criminal with a lot of knowledge of the research on
the polygraph, though, the test would be less likely to detect lying,
assuming the criminal believed (correctly) that it's not accurate.

The polygraph is an interesting case of measurement and error in the sense
that it demonstrates ideas of reliability of measures and external validity
(are we measuring what we think we're measuring).  I think this is more
complex that you want to get in an exhibit, though.

One concern I have is that by including a polygraph in an exhibit without
debunking it you are tacitly lending validity to the idea that it is a valid
scientific tool that accurately measures what it is claimed to measure.  

My other concern is for my discipline itself, in that I think psychology
often tends to be misrepresented in science museums or represented in ways
that are highly skewed toward a very old definition of the discipline.  I'm
currently doing a research study on the representation of psychology in
science museums and have been collecting data on psychology-related
exhibits.  My hope is to get both psychologists and museums interested in
more collaborative work to make some of the more interesting recent research
and concepts in psychology available to the public.  In my mind, reinforcing
the public perception of the polygraph as legitimate psychological science
is a negative development in the public perception of psychology.  Many
people tend to see psychology in a way that is almost akin to "magic."  If
you tell someone you're a psychologist they start to think you can read
their mind or something.  One of the goals of psychology is to help dispel
the power of "magic" in people's minds and to ignite interest in science.  

I think there MAY be ways to do this with a polygraph in a museum, but I
think it's more likely that many people would come to a conclusion that is
opposite to what you are trying to convey, so I'm doubtful that it's "worth
it."

Suzanne Mallery
Assistant Professor, Psychology
La Sierra University
Riverside, California

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