Dr. Dorothy McCoyMaintaining Your Mental Edge
with Dr. Dorothy McCoy

Truth detection: The holiest of human grails

Scenario: You are investigating the disappearance of an attractive young woman. Her husband, with tears in his eyes, says, “In the morning I’ve been taking the dog down to the park where she walked. It was our time. It’s a way for me to experience her now. Often. . .I can’t make it very far."

Would you have believed this man?
Scott Peterson listens during his pretrial hearing at Stanislaus County Superior Court in Modesto, Calif., Tuesday, May 27, 2003.


According to the prosecution at his headlining trial, Peterson killed his wife, Laci and their unborn son, Conner. Peterson, who exhibits various psychopathic tendencies, deceived Laci, his girlfriend Amber Freye, his parents and siblings, Laci’s family and a sympathetic public.

Detecting Deception

As a species we are pitifully poor lie detectors. One would think, since we have been communicating for thousands of years, we would have devised ways to accurately distinguish between a falsehood and the truth.

Scientists are interested in knowing which professionals are the most consistent lie detectors. Researchers also want to define the elusive gestures, facial expressions, eye ticks and/or body tension that correctly signal veracity (or the lack thereof). The useful data of roughly 100 years of research on lie detection are meager at best. I can guess who will win the big game on Saturday afternoon about half of the time. Our ability to detect deception is comparable.

Britton Chance, professor emeritus of biochemistry and biophysics at the University of Pennsylvania in Philiadelphia,is testing a headband outfitted with near-infrared light emitters and detectors to "see" blood-flow changes in the brain when volunteers are lying.(AP Photo/Jacqueline Larma)
Are law enforcement officers, psychologists and judges better at detecting lies than the average person? No, they are not. As studies have shown, these professionals are no more accurate than stockbrokers, cab drivers or attorneys. There is one exception — Secret Service agents have scored quite well at reading dishonesty in body language and verbal clues. Evidently their training prepares them for sniffing out deceivers.


If we could accurately, consistently recognize truthfulness, our multi-billion dollar judicial system would be slashed dramatically. We would not wonder if the O.J. Simpsons and Scott Petersons of the world were guilty. If suspects were innocent they would never become suspects. The Peterson trial cost taxpayers an overwhelming $4 million. The pitiable, overburdened California taxpayers spent more than twice that on the O.J. Simpson fiasco in 1994. This trial also divided Americans into two opposing camps:  The “he's guilty as sin” camp and the “he was framed” camp.

The Quest for Truth

Diogenes, the "Cynic" of the classical Greek world who scorned human beings for their deceitfulness, is the most famous seeker of authenticity, but he's not the only one. Ever since humans first organized into communities, finding a reliable instrument or system for analyzing the truth/lie continuum has been a priority.

Each civilization has attempted to resolve this quandary. One of our modern attempts is the polygraph, which dates to 1918. Polygraphs are becoming more common as a dimension of pre-employment assessments. Though used in the legal system, polygraph results are not admissible in court as evidence (except under some very specific circumstance). This is primarily because results can vary according to the operator’s experience, training, skill and sensitivity.

According to legend, the polygraph is based on an ancient Chinese test of honesty. The accused was given a hand full of rice to hold in his mouth. The theory was, if the subject was guilty his mouth would be dry and he would have difficulty spitting the rice out. However, guilt is not the only emotion that can initiate an interruption of saliva production. The autonomic system which controls glands can be affected by any stressor, including fear and anxiety. The National Polygraph Training Center for the U.S. military is located at Ft. Jackson, South Carolina. I took a tour of the school and heard a presentation by one of their dedicated, highly trained staff members. The good news is, they are bringing lie detection into the 21st Century. Watch for new developments in that area.

During the Cold War, the CIA and other secret squirrel organizations used so-called truth serums to gain information from reluctant spies. Many barbiturates fall in the truth serum category, including scopolamine, sodium amytal and sodium pentothal. The “truth serums” are no longer used by Ray Ban-wearing feds because the drugs proved to be unreliable. In addition, many barbiturates, such as sodium amytal have a high potential for dependence and addiction. Side effects and interactions with other medicines are not uncommon.



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