Lie Detector Machines

Modern lie detection boils down to a machine-enhanced capacity to detect minute bodily perturbations, together with the professional skill to interpret their mental correlations. The machine most commonly used in lie detection is the polygraph. Quickly reviewing some of the highlights of its development, the polygraph was foreshadowed in the mid-nineteenth century when Italian criminologist Cesare Lombroso utilized measures of pulse and blood pressure in the interrogation of suspects. By 1908, the well-known psychologist, Hugo Munsterberg, was advocating the use of blood pressure for detecting deception in the law courts. William M. Marston, one of Munsterberg's Harvard students, claimed to have discovered a specific physiological response that accompanied lying. An avid publicity hound, he made several unsuccessful efforts to apply his technique in the investigation of the kidnapping of the Lindbergh baby. Ultimately, Marston went on to other pursuits and, under the pseudonym of Charles Moulton, created the comic strip character "Wonder Woman."^[12]

Marston's claim that a specific physiological response exists for deception did not survive, but exploration into more general links continued. John A. Larson developed a large and unwieldy machine capable of providing continuous measures of blood pressure, pulse, and respiration rates. Working closely with the criminologist and police chief, August Vollmer, he used the instrument for investigations in the Berkeley Police Department. His most famous success was a shoplifting case in the early 1920s. The culprit was known only to be one of thirty-eight women living in a certain dormitory. Larson interrogated all of them with the assistance of his machine and found that one reacted much more strongly to questions about the thefts than the other thirty-seven. Confronted with the findings, she made a full confession.^[13]

A high school student named Leonarde Keeler, fascinated by police work, used to spend his spare time around the Berkeley Police Department in those days. He took a keen interest in Larson's and Vollmer's experiments, and in 1926, Keeler developed the first compact, portable polygraph machine. It remains the

prototype for current models. Keeler went on to become one of the founders of the lie detection profession. Based in Chicago, he utilized his polygraph extensively in criminal investigations during the 1930s and 1940s. Keeler developed some of the formats for lie detector tests that are still in use and founded the first polygraph examiner training institute as well as a company that manufactures polygraph machines.^[14]

The polygraph is a device that simultaneously monitors several different physiological processes. The machine is attached to the subject in several ways. An expandable band is placed around the chest (and perhaps a second one around the upper abdomen) to measure breathing patterns. A blood pressure cuff is applied to the upper arm and inflated to about halfway between the diastolic and systolic pressure, to measure fluctuations in blood pressure and pulse rate. A small clip placed on a fingertip measures galvanic skin response (GSR): an electric current, so small that the subject cannot feel it, is passed through the clip, and changes in conductivity reveal variations in the subject's perspiration. Another, similar clip may also be applied to measure pulse and blood volume in the fingertip. Readings from these sensors are recorded by fluctuating pens on a long sheet of graph paper that moves steadily beneath them. During the course of the test, the examiner writes the number of each question on the graph paper as it is asked. This makes it possible, when the chart is analyzed, to connect physiological responses as recorded on the chart with the various questions.

No one (at least, no one since Marston) claims that deception can be measured directly. As with all tests, lie detection deals in representations. In the case of polygraph tests, these representations take the form of a chain of causality leading from prevarication to anxiety or psychological stress and then to physiology. As already noted, the general theory is that emotional stress produces variations in one or more of the physiological functions monitored by the polygraph. One form of stress that may produce such physiological variations is apprehension about being caught in telling a lie. Assuming that other reasons for stress can be ruled out, significant changes in the polygraph tracings that accompany the response to a given question (when a subject

"hits" on a question, in the parlance of the trade) may be interpreted as signifying deception.

The type of signification that operates in polygraph tests is metonymy. The presence of an observable effect metonymically signifies the co-presence of its cause, even if the cause is not observed directly. Precisely in the same way as smoke signifies fire, in the logic of the polygraph, certain physiological perturbations, properly analyzed, signify deception.

Stanley Abrams sets out to provide a more detailed account of the rationale behind polygraph examinations.^[15] In an apparent effort to drench his discussion in as much science as possible, he even includes information on the human cell and the operation of neurons, although, alas, no relation between these particular matters and the operation of the polygraph is identified. In the more pertinent part of his account, Abrams keys polygraph to the "fight or flight" reaction that has been indelibly imprinted in human beings and other animals over eons of evolution as an adaptive response to situations of danger. The threat of being discovered in a lie provokes this reaction, which consists of a set of physiological changes that prepare the individual to fight or to run away. "Vasoconstriction takes place in the peripheral blood vessels and causes an increased flow of blood to the skin, thereby allowing for a dissipation of the heat engendered by muscular effort and fostering a reduction of blood loss should injury occur."^[16] Moreover, sweat appears on the palms and hands "to aid in locomotion or grasping. . . . Stronger contractions of the heart send more oxygenated blood through the body and an additional blood supply is directed to the skeletal muscles allowing for a more effective utilization of the arms and legs."^[17] These developments are monitored by the various measuring devices of the polygraph. Therefore, lie detection by the polygraph, as Abrams cogently points out, produces an interesting twist on evolutionary patterns of self-preservation: "ironically, those same responses that typically serve to get the individual out of trouble get him into difficulty if he is deceptive during a polygraph test situation."^[18]

Although this polygraph machine is the one in general use today, technological elaborations have been tried from time to time. The Darrow Behavior Research Photopolygraph (fig. 3), mar-

Figure 3.
Darrow Behavior Research Photopolygraph. From Paul V. Trovillo.
"A History of Lie Detection." Journal of the American Institute of Criminal
Law and Criminology 29 (1939):874.

keted half a century ago, seems to have been attached to the subject's body in every way imaginable. Apparently, the apparatus used by the CIA, which makes frequent use of instrumental lie detection, is similar. An informant said that it expands the number of physiological characteristics monitored from three or four to twenty-eight and that an individual wired up to it "looks like an astronaut." At the other extreme, Israel's Weizmann Institute has developed a machine that does not touch the subject's body at all. It measures palpitations of the stomach remotely, by microwaves, on the theory that such movements increase in frequency when an individual is lying. The device is in use at border checkpoints, where individuals may be subjected to lie detection without their being aware of it.^[19]

Lie detection by remote sensing, of course, obviates the necessity to hook the subject up to clips, tubes, and wires. These attachments frequently provoke a good deal of consternation.

Several polygraph examiners told me that it is frequently necessary to assure subjects that the machine will not give them electric shocks; occasionally, people observe with apprehensive humor that they feel like they are going to the electric chair.

The psychological stress evaluator (PSE) is a type of lie detector machine that attaches nothing to the subject's body. It is designed to analyze stress in the voice. As its history was explained to me by a PSE examiner, the device was invented by two army officers, Charles McQuiston and Allan Bell. They wanted to give lie detector tests to suspected double agents and others in the jungles of Vietnam and found that the polygraph was not suitable for such use in the field. With the PSE, one asks the same sort of questions as would be used in a polygraph test, but the subject answers (yes or no) into a tape recorder microphone. The tape is then run, at one-quarter speed, through a special analyzer that produces a chart composed of closely packed lines of varying heights and positions on a narrow strip of paper similar to that used in cash registers. The expert studies the chart for points of vocal stress or tension, not audible to the ear, that may be found in the answers to certain questions on the test.

The general theory behind the PSE is identical to that informing the polygraph: anxiety about being caught out in a lie produces certain physiological responses (this time in the voice), and these can be detected and recorded by the machine. In an interview, a PSE examiner provided a more detailed rationale that (in contrast to Abrams's reliance on the fight or flight reaction) trades on the relation between the subconscious and conscious sectors of mind. It is an outstanding example of the tendency of lie detection to disarticulate the person into fragments that are then set against each other. The subconscious mind, he explained, is like a computer data bank with no discriminating controls. In response to any question, the subconscious simply dumps everything it has on that topic. The conscious mind, which is a highly discriminating gate-keeping device, reviews what the subconscious has produced and decides what to reveal. The verbal answer to any question is what the conscious mind lets pass. Even if a question has potentially damaging implications for the self, such as whether one stole something (when one in fact did

steal it), the subconscious foolishly churns out the correct answer: yes. The conscious mind, however, in effect says (and this is a quotation from the PSE examiner), "You dummy, I'm not going to say that. It will get me in trouble." Hence the subject gives a false answer to the question: no. Whenever one lies, then, there is a difference between the responses of the unconscious and conscious components of the mind. That difference produces psychological tension, or stress, and that in turn affects the voice in a way that is measurable by the psychological stress evaluator. The logic of signification is the same as for the polygraph, operating on the assumption that perceptible effects signify, by metonymy, concealed causes. The word "stress," incidentally, was frequently used both as a noun and as a verb by the two PSE examiners I interviewed. Whereas polygraph examiners tend to say the subject "hit" on a certain question, the PSE examiners would say the subject "stressed" on it.

As with the Israeli remote sensor, it is possible to give PSE tests without the subject being aware of it. A polygraph examiner told me that some insurance companies record telephone conversations with policyholders concerning loss claims so as to subject them to analysis by the PSE. Another pointed to a PSE tape prominently displayed on the wall of his office. It was, he said, the voice of Patty Hearst as recorded from a telephone conversation while she was with the Symbionese Liberation Army, and he indicated several points on the chart where she stressed.

The lie detection profession itself has stressed on the question of the PSE. PSE examiners argue that their newer and simpler technique is as accurate as the polygraph. Polygraph examiners, who are much more numerous and whose technique is more common, tend to dismiss the claim, often with expressions of contempt not unlike those that critics of the whole idea of lie detection level against the polygraph. Thus an unfriendly schism has emerged between PSE and polygraph examiners.