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The Sexual Lie Detector

Why are therapists using a coercive, unsupported intervention?

The polygraph (lie detector) is a good example of a test that was once seen as both valid (measuring what it is supposed to measure) and useful. But, modern research on the polygraph has revealed that its scientific underpinnings are weak, and it doesn’t actually measure truth-telling.

Challenges and concerns regarding the polygraph

The modern polygraph is now recognized as being merely a measure of physiological arousal, which is only indirectly and inconsistently related to the truthfulness of a person’s speech.

Physiological arousal, as measured by things like heart rate and sweatiness, is, in many people, evidence of feelings such as anxiety, guilt, and shame. These feelings are sometimes related to deception, but more often are evidence of a person's feelings about the information or question—and thus have more to do with the moral and personal issues with the answer than whether or not the answer is actually true.

I know a man who failed a polygraph question about the use of marijuana—not because the man had ever used it, but because he felt guilty and embarrassed that he has never used the drug, being of a generation that made marijuana “cool.”

As a result of such concerns, along with serious challenges to the scientific validity of the test, the polygraph is no longer seen as an objective or useful clinical tool and is usually no longer admissible as legal evidence. Federal law prohibits mandatory use of polygraphs in employment, and polygraph results are rarely allowed in court anymore.

However, polygraphs are popularly used in monitoring convicted sex offenders and by therapists/practices focused on sex addiction and sexual infidelity.

Polygraphs and sex offenders

Polygraphs are used often in the monitoring of convicted sex offenders, with polygraphs used to compel disclosure of victims, and at a maintenance level, to force them to disclose any recent offenses while on parole.

Ethically, these practices raise strong concerns about forcing individuals to self-incriminate. Also clinically, I've always felt that it is inappropriate to use force and coercion on people who used force and coercion to hurt others. "An eye for an eye" is a matter of justice—not a clinical or therapeutic strategy. Unfortunately, such approaches can even worsen these offenders' risk of reoffending by increasing their feelings of helplessness, isolation, and anger and by teaching them that coercion is acceptable.

Polygraphs and sexual infidelity

The general public is often unaware of the polygraph's limitations, putting them at risk of being hoodwinked by clinicians who suggest that the polygraph can be an effective tool in dealing with relationship issues.

Polygraphs are recommended by clinicians and businesses targeting concerns of sexual infidelity and behavior problems, with claims that the polygraph can “keep sex addicts honest,” determine “the extent of infidelity,” and monitor whether your “sexually addicted spouse is maintaining their sobriety.”

Such strategies attempt to exert control of individuals' sexual and relational behaviors through external control, ie, "you will get caught" as opposed to creating internalized values against these behaviors. Such external controls, unfortunately, infantilize and excuse the choices of these individuals.

Numerous sex addiction therapists and writers refer to sex addicts as “world-class liars” or "practiced liars” and offer the polygraph as a way to manage these people’s deceptiveness. Clinically, and ethically, I'm stunned to see licensed mental health therapists who publicly denigrate and shame the people they claim to treat.

Polygraph tests for such issues commonly cost between $150-$400, and sex addiction clinicians refer these out, offering them as ways in which people can feel more comfortable trusting their formerly unfaithful spouse. But do they work in this manner? Penn and Teller once addressed this issue in their HBO show and filmed a man sent to polygraph testing by his fiancée, who was worried that he had cheated on her. The show also demonstrated ways to confuse and "fake" the polygraph. One former police officer was convicted for running a website where he taught people how to hoodwink the lie detector.

Research on the polygraph is a complex, nuanced area, with some evidence of value and usefulness in some specific limited areas. However, its value and effectiveness in personal matters, relationship issues, and as a test and treatment of infidelity remain completely untested. Because the polygraph is extremely sensitive to issues related to guilt and shame, its value in matters of sexual infidelity is extremely questionable.

In 2014, research on the perception of the polygraph in legal issues showed that the polygraph is generally seen as invalid by most juries, except in one specific area: divorce cases. In this study, polygraph results had a decidedly negative impact on divorce cases, despite its serious limitations.

Polygraphs serve as a form of coercion, shame, and external control

The use of the polygraph in therapeutic treatment of relationship conflict over sexual issues and behaviors is, at best, experimental without empirical support. Clinicians using and recommending the polygraph in such ways should be informing their patients of these extreme limitations and the likelihood of unreliable results.

The clinical use of the polygraph is merely a further extension of morality and shaming around sexual behaviors, violations of monogamy, and guilt over eroticism. Licensed mental health clinicians, who purport to be in the business of helping people, have no place involving this coercive, invalid, shaming tool in their therapeutic practices. It serves as a form of external control and "a way to catch and enforce monogamy" in a manner that is neither therapeutic nor evidence-based. These therapists can be more effective, and more ethical, by helping patients to develop internal values of sexual integrity, including honesty, mutuality, consent, negotiation, and self-awareness.

More from David J. Ley Ph.D.
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