THE LIE DETECTOR
This detestable machine, the polygraph (the etymology of which shows that the word means "to write much," which is about all that can be said for it).... It is such an American device, such a perfect example of our blind belief in "scientism" and the efficacy of gadgets; and ... so American in the way it produces its benign but ruthless coercion.
-- WILLIAM STYRON1
A deceptive subject might try to beat the lie test by inhibiting his physiological reactions to the relevant questions. Some people can attenuate their responses even to very strong or painful stimuli if they know when the stimulus is coming. 2 Because the pattern of a control question lie test is fixed, a sophisticated subject should be able to tell when the relevant questions are about to be presented. Some persons have much better control of their reactions than others do. There are even ethnic differences. When Bedouin tribesmen of the Negev desert were examined on the polygraph, they were found to be far less reactive than Israeli Jews, whether of Near Eastern or European origin. 3 Moreover, most people will become habituated to any stimulus, such as a question, that has been frequently repeated, reacting less strongly to that stimulus than they did at first. A criminal suspect who has been extensively interrogated might, as a result of this habituating repetition, become less reactive to the relevant questions on a lie test administered later.