In an essay published in Science for November 3, Steven Aftergood, a scientist who in 1997 directed a project organised by the Federation of American Scientists on the evaluation of security measures, maintains that "most scientists who have studied polygraph testing are deeply sceptical of its usefulness in screening employees as a way to enhance security". Despite this, many of the professionals concerned with national security remain deeply committed to its continued application.
The question must be, argues Aftergood, does the polygraph work? In fact the answer must be that it accurately measures cardiovascular activity, depth and frequency of respiration, and changes in skin conductivity due to perspiration. In addition it records how these data change when the subject is challenged by verbal stimuli. How an examiner interprets such changes is another matter. Supporters of the technique argue that the test has deterrent value and helps to discourage casual indiscretions. It is reported that some of those who come through the ordeal unscathed may come to regard it as an initiation ritual of mystical significance.
The critics maintain that no specific psychophysiological response to a question can with certainty be associated with lying or deception in the questioned. The critical uncertainty factor in testing is the meaning allotted by the examiner to the data elicited. The outcome is that some individuals are inevitably going to be deemed deceptive without justification, while others who are crooked but confident will pass the test without doubts regarding their reliability.
In 1998 the United States Supreme Court ruled that "there is simply no way to know in a particular case whether a polygraph examiner's conclusion is accurate". It appeared doubtful whether polygraph testing had a deterrent effect on dishonest subjects. The outcome of the latest security controversies is likely to be that more individual scientists feel entitled to express doubts that the official national security policies hold credibility. That is a lamentable situation, and one that might have been avoided by greater objectivity and freedom from bias.