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 risk being fired or having their decision held against

them in some way.

According to the American Polygraph Association (APA), an