Perhaps the best known method of deception detection is the polygraph technique, often inaccurately referred to as the "lie detector." However, other methods exist, such as -- hypnosis, narcoanalysis ("truth serum"), PSE (psychological stress evaluation), and P300 brain wave "fingerprinting." Although these other methods will be discussed briefly, most of this lecture focuses on the polygraph.

HISTORY OF THE POLYGRAPH

Lombroso, the founding father of criminology in 1895, was the first to experiment with a machine measuring blood pressure and pulse to record the honesty of criminals. He called it a hydrosphygmograph. A similar device was used by Harvard psychologist William Marston during World War I in espionage cases, who brought the technique into American court systems. In 1921, John Larson added the item of respiration rate, and by 1939, Leonard Keeler, one of the founding fathers of forensic science, added skin conductance and an amplifier, thus signaling the birth of the "polygraph" as we know it today.

The polygraph is a sound and reliable technique for detecting deception. The vast majority of studies into the reliability of polygraph testing estimate it at least at 90% or higher. Numerous research findings, and works in the field of medicine, have justified the connection between involuntary (sympathetic nervous system) physiological changes and emotional states related to truth-telling or deception. Unfortunately, mostly through historical accident, polygraph exams are not legally admissible unless there is a stipulated agreement prior to trial. There's also some questionable validity (if something measures what it purports to measure) in the use of polygraph for noncriminal purposes, such as preemployment screening, drug testing, and so forth. Ironically, polygraphs are more commonly found in these noncriminal, civil law areas. Police departments, for example, make extensive use of them in their personnel policies, and they are also common with sensitive, security jobs in government and business. Their use in these contexts ignores the fact that these were not what the tests were designed for (criminological positivism), and instead, substitutes the Teddy Roosevelt idea that a public safety employee has nothing to hide anyway (under color of law or presumption of innocence). Privacy rights and protections against self-incrimination are much less guaranteed in civil cases or civil matters.

It must be remembered that this is the area that gave us the Frye test for admissibility (Frye v. United States 1923). It's worth looking at the language of Frye in some detail:

Just when a scientific principle or discovery crosses the line between experimental and demonstrable is difficult to define. Some in this twilight zone, the evidential force of the principle must be recognized, and while courts will go a long way in admitting expert testimony deduced from a well-recognized scientific principle or discovery, the thing from which the deduction is made must be sufficiently established to have gained general acceptance in the particular field in which it belongs.

The court in Frye decided that the polygraph belonged in the fields of physiology and psychology, but at the time (and to this day still), neither field claims the technique. An interdisciplinary field called "psychophysiology" emerged during the 1970s, but it consists largely of academics with no practical field experience in dealing with criminal suspects. On the whole, their research, while methodologically sound and statistically sophisticated, tends to involve studies in the truthfulness of college students (convenience sampling). The field of psychology tends to treat the polygraph as another instance of psychometric tests, and one of the most fundamental principles of psychometry is that each and every subject should get the exact same questions in exactly the same way. All of this flies in the face of polygraph examiners who argue, understandably, that in the hands of a "master", with experience in dealing with criminals and flexibility in being able to condition and question suspects differently, the polygraph technique is highly valid and reliable.

As it stands now in 2000 (and there has been numerous, conflicting case law since 1923, but no definitive Supreme Court ruling), polygraph tests in the vast majority of jurisdictions follow a stare decisis (let the precedent stand) pattern in which they are not admissible (per se inadmissibility) at any criminal trial unless there has been a prior stipulation by both prosecution and defense to agree to submit the results of such examination. The logical outcome of this is that both sides should agree on the undisputed expertise of a single examiner, or that the prosecution should use its own examiner and the defense should use its examiner, but the power to choose rests with the defense, a phenomenon referred to as the "friendly examiner" syndrome. Studies have not borne out the truth of this syndrome, but it theoretically refers to the idea that a deceitful suspect who takes a polygraph voluntarily at the request and arrangement of their own attorney will stand a better chance of appearing truthful.

The law is even more complicated than per se inadmissibility. Because of stare decisis and the Fifth Amendment, the state cannot require a criminal suspect to submit to a polygraph, even under some pretrial stipulated agreement. If there is a state-sponsored examination, it must be voluntarily taken, and then if the results are negative, they are generally inadmissible because the test was given under coercive circumstances. The fact of the matter is that only positive test results ever get seen at trial. For this reason, lawmakers in about half the states (including North Carolina especially) have decided to NOT allow polygraph evidence to be admitted in criminal cases at all, for any reason, stipulated agreement or otherwise. A small handful of other states (most notably New Mexico) have gone the opposite direction, permitting polygraph results in criminal cases, pursuant to stipulation and over objection, especially if the test results were unfavorable to the defendant.

Lie detection methods have been used for years by police interrogators. Physiologically, when a suspect lies about their involvement in crime, it's fairly easy to notice a flushed face, throbbing of the carotid artery, dryness of the mouth, sundry other clues. Psychologically, verbally, and nonverbally, there are other clues and cues. The assumption behind all lie detection methods is that there's a natural interaction between mind and body, and depending upon the individual and their level of involvement, deceptive suspects will utilize certain mental, emotional, and physical defense mechanisms that are dependent upon the amount of stress they're under or what danger they perceive themselves to be into. Now, that's a big assumption, and the phrase "defense mechanisms" might be better called the "psychological set" to rule out any idea that the technique is psychoanalytically grounded, which it is not. Polygraph exams are believed to offer individual, rather than class, evidence because through the years, developmentally, a person develops set ways of reacting to reacting to stressful or threatening situations. During a polygraph, an examiner is always paying attention to these fundamental clues and cues, developing a sense of the suspect's values, beliefs, motives, and attitudes.

The machine part of a polygraph examination is designed to pay attention to the actions of the nervous system, particularly the autonomic nervous system, and then certain sympathetic members of the autonomic system which alert the body to stress or threatening situations. The machine has components that measure the following:

The machine is not just operated. The examiner should be a person of ability, experience, education, intelligence, and integrity who uses the machine in a predetermined manner. There are three (3) phases of the test procedure: (1) a pretest interview; (2) chart recording; and (3) diagnosis. Beforehand, the examiner is provided with all relevant information regarding the case, such as the criminal charges against the person and the statement of facts. They then spend some time alone preparing a pool of test questions that are neither too broad nor too specific. Anything calling for an opinion or belief that can change with time or motivation is ruled out as a possible test question, as is anything vague. The pool of questions should focus on a single incident, the facts, and narrowly defined issues of disputed action, not intention.

During the pretest interview, the examiner will condition the subject by clarifying the purpose of the test, reassuring them about its objectivity, and/or defining terms that will be used. Also, a control question will be developed and selected. A control question is unrelated to any legal issue, but it addresses a related behavior. For example, with a crime of violence, a control question might be "Have you ever lost your question or done things you regret?" Relevant questions are those that have a direct bearing on the case, and irrelevant questions have no bearing whatsoever, but can only be answering truthfully ("Are you sitting in a four-legged chair right now?").

Generally, a series of 9-10 prepared questions are asked, allowing about 10 seconds following an irrelevant question and 15-20 seconds following a relevant or control question. It's also standard to run through all questions a minimum of three times before a diagnosis is attempted.

Diagnosis is made by verifying other clues and cues with the chart. A truthful subject's chart will show emotional attention was paid toward the control questions and deflected away from the relevant questions. A deceptive subject's chart will show emotional attention directed toward relevant questions and away from control questions. The following illustrations might be helpful:

The top line is respiration and the second line blood pressure. Questions #4 and #7 were irrelevant, and show the most reaction.

Question #4 was irrelevant and question 6 was a control question, the latter showing the most reaction. The relevant questions, #3 and #5, show emotional attention in their most common form, a steady increase or decrease in the baseline.

In cases where the suspect is trying to "beat" the polygraph or confuse the examiner in some way, you need to also look at the third and fourth lines, skin conductance and cardiovascular change. The relevant questions were #4 and #6, which show a response, but there's a lack of response to control questions #5 and #7.

In cases where the suspect is trying to mislead the examiner because they are trying to feign amnesia, mental illness, or other mental block indicative of confusion, the pattern results are as above, with high-ranging plateaus. It is rare to get this kind of pattern from a truthful subject.

Only when an accused person or eyewitness suffers from a clear case of amnesia will the court consider the use of hypnosis. Defense counsel usually calls for it (in the case of suspects), and is under an obligation to have the results or psychiatric testimony corroborated by an independent third party. Hypnotically induced testimony is inadmissible in court, and hypnotically refreshed or recollected memories are highly controversial.

In a 5-4 decision, the Supreme Court in Rock v. Arkansas (1987), ruled that there should be no per se inadmissible approaches to hypnotically refreshed testimony, that these constitute arbitrary restrictions and prohibit a person from being able to testify in their own defense. Most states now follow a case-by-case approach, and controversy is the norm in the scientific literature.

Controversy and disagreement reign over the use of various drugs -- scopolamine, sodium amytal, and sodium pentothal -- to reliably produce truthfulness. All such drugs simply inhibit control of the nervous system and reduce inhibitions. All courts refuse to admit truth serum evidence, the leading case coming from the New Jersey Supreme Court, State v. Pitts (1989), which disallowed the results of a sodium amytal interview, ruling that it is not a valid scientific technique.

PSE, sometimes called voice stress analysis, is based on the use of a certain machine developed in the late 1960s that presumably detects "guilt-revealing", laryngeal microtremors which exist in the voice and are associated with stress and lying. Most research has produced negative or mixed findings of a relationship between microtremors and deception. Like the polygraph, the key to success is the preparation of prepared test questions. A handful of states, like Arkansas and Louisiana, have licensing requirements for PSE evaluators, but it's generally conceded that PSE is not admissible in civil or criminal cases and only useful in investigative settings.

Neuroscientist Lawrence Farwell, who runs a Brain Wave Institute in Fairfield, Iowa patented this technique in 1995, which has attracted the attention of the FBI and CIA as a better way to detect moles. Iowa judges are also fond of admitting the technique, even though Iowa is a state where the polygraph is outlawed. The basic principle is that different regions of the brain light up when people tell the truth or lie, and further, that different regions are activated depending upon the type of lie. Dr. Farwell's research, however, looks at a specific type of electrical brain wave, called P300, which activates when a person sees a familiar object. For example, if a murder suspect is claiming an alibi, then their P300 wave won't activate when they are shown the murder weapon. The technology is promising in that the research indicates the brain stores visual images. In the P300 test, a subject wears a headband of electrodes and faces a computer screen. In similar tests, a subject wears a helmet of electrodes, and experts try to make interpretations from a record of what areas of the brain "light up" or receive intensive blood flow.

PRINTED RESOURCES
Hollien, H., L. Geison & J. Hicks. (1987). "Voice Stress Evaluators and Lie Detection" Journal of Forensic Sciences 32(2):405-18.
MacDonald, J. (1955). "Truth Serum" Journal of Criminal Law & Criminology 46:259-69.
Moenssens, A., J. Starrs, C. Henderson & F. Inbau. (1995). Scientific Evidence in Civil and Criminal Cases. Westbury, NY: Foundation Press.
Nachshon, I. et al. (1985). "Validity of the Psychological Stress Evaluation" Journal of Police Science and Administration 13:275-35.
Nardini, W. (1987). "The Polygraph Technique: An Overview" Journal of Police Science and Administration 15:239-49.
Orlansky, J. (1962). An Assessment of Lie Detection Capability. Washington D.C.: Institute for Defense Analysis.
Orne, M. (1984). "Hypnotically Induced Testimony" in E. Loftus (ed.) Eyewitness Testimony. NY: Free.
Reid, J. & F. Inbau. (1977). Truth and Deception: The Polygraph Technique. Baltimore: Williams & Wilkins.