Homo Sapiens have yearned for a reliable and consistently correct way of finding
out if one is telling the truth since ancient times. “Early societies used torture. Statements
made by a person on the rack were considered especially believable.” (Jussim, pg.65)
There was also trial by ordeal, which was based on superstition. For instance, if there
were two suspects for one crime, it was thought that the innocent would be stronger in
combat and thus vanquish a guilty opponent.
This example shows how it was done long ago. “The ancient Hindus made
suspects chew rice and spit it into a leaf from a sacred tree. If they couldn’t spit, they
were ruled guilty. Although this procedure long predated the modern lie detector, it was
based-knowingly or not- on assumptions about psychological stress much like those that
support polygraph examinations today. The ancient test depended on the fact that fear
makes the mouth dry, so rice would stick in a guilty person’s mouth. For the procedure to
work, the subject had to believe in its accuracy and, if guilty, had to be anxious about
being caught in a lie.” (Ansley, pg. 42)
The modern polygraph is said to measure the subject’s “internal blushes” in much
the same way. It does not really detect lies-only physiological responses. The theory
behind the polygraph is that lying always heightens these responses. When taking the test,
subjects are hooked up to a briefcase-sized machine by means of several attachments.
usually, a pneumatic tube goes around the chest to measure respiration, a cuff squeezes
one bicep to monitor blood pressure, and electrodes are attached to two fingertips to
determine the skin’s resistance to electrical current (which is related to how much the
subject is sweating). An examiner, or polygrapher, quizzes the subject. As the subject
answers the questions, the machine draws squiggles on a chart representing physiological
responses, which are supposed to clue the examiner in to the subject’s lying, or truthful,
ways. Just as the ancient Hindu was betrayed by a dry mouth the modern polygraph
subject is said to indicate that he or she is lying by breathing harder or having a racing
pulse. (In arriving at a conclusion about a person’s deceptiveness, some polygraphers also
use their own subjective observations of the person’s behavior.)
The test will not work, though, if the subject does not believe in the procedure. If
the subject doesn’t not think the machine can tell the examiner anything, then he or she
won’t be anxious and won’t show the heightened responses that the machine is designed
to record. Because of this, the examiner will often use deceptive tricks to impress the
subject with the polygraph’s alleged accuracy.
Modern polygraphy got its start in Chicago in the 1930s, where it was used in
criminal justice investigations. Now it has a wide range of other applications, including
screening job applicants and employees, conducting intelligence investigations in federal
security departments like the Central Intelligence Agency, and trying to uncover the
source of unauthorized disclosures to the press of government documents or information.
The strategies used by polygraphers vary from one application of the machine to
another. in pre-employment screens, subjects are typically asked a series of about twenty
questions. “Irrelevant” questions like “Is your name Fred?” serve to put the subject at
ease. Typical “relevant” questions are: have you ever been convicted of a crime? Stolen
from a previous employer? is all the information on your employment application correct?
Do you take illegal drugs? This series is repeated, and if physiological responses to
particular relevant questions are constantly and significantly higher than responses to
others, the subject is reported as “deceptive.”
Investigations into specific incidents are more complicated. Tin these, “relevant”
questions concern only the alleged wrong doing-for instance, “Did you steal the missing
$400?” To determine truthfulness, polygraph responses to these questions are compared
with responses to other questions- called “control” questions-that are provocative but do
not relate to the incident.
The use of polygraphs in the work place greatly increased over the last fifteen
years, and now over two million of them are given annually in the United States.
Seventy-five percent of them are administered to job applicants. Other tests are given
periodically or randomly to employees or as part of an investigation in the wake of a theft
or act of sabotage. Although subjects technically submit to testing “voluntarily” -
generally signing a release saying they are willing to undergo such an examination- they
actually have few options. Applicants who refuse a screen are not likely to be hired, and
even long-time employees who refuse