The Effects of Physical Countermeasures on the Physiological Detection of Deception

First systematic laboratory study of physical countermeasures, finding trained subjects could reduce detection rates but countermeasure use was partially detectable.

Controlled experiment training subjects in physical countermeasures (tongue biting, toe pressing) during comparison questions.

Honts, Hodes, and Raskin's study demonstrated that approximately 50% of trained subjects could defeat the test using physical countermeasures, but also showed that countermeasure use itself produced partially detectable patterns. This dual finding revealed both the vulnerability and a potential solution.

The finding that countermeasures are partially detectable opened research into countermeasure detection methods that continue to develop.

Background & Context

The 1985 Honts, Hodes, and Raskin study stands as a watershed moment in polygraph research, representing the first systematic laboratory investigation of physical countermeasures designed to defeat the Control Question Test (CQT). Prior to this research, the polygraph community had largely assumed that deceptive subjects could be reliably identified through physiological monitoring, with little empirical examination of whether examinees could manipulate their responses.

This study emerged at a critical time when polygraph testing was expanding in law enforcement and employment screening contexts. The research team, led by Charles Honts at the University of Utah, sought to answer a fundamental question that threatened the validity of polygraph testing: Could guilty individuals be trained to systematically alter their physiological responses and evade detection?

The investigation filled a crucial gap in the scientific literature by providing the first controlled experimental evidence on whether simple physical maneuvers—such as biting the tongue or pressing toes to the floor—could effectively augment physiological responses to control questions and thereby distort test outcomes.

Research Design & Methodology

The study employed a rigorous two-experiment design to systematically evaluate countermeasure effectiveness. Experiment I involved 48 undergraduate students divided into 4 groups, 3 of which enacted a mock crime. Two guilty groups were trained to use either tongue biting (pain countermeasure) or toe pressing (muscle countermeasure) during control question zones of the CQT.

Experiment II involved 57 subjects divided into 3 groups, 2 of which enacted a mock crime, to assess the effects of additional training and concurrent use of both countermeasures. The second experiment provided more intensive countermeasure instruction and examined whether combining physical techniques would prove more effective than single methods.

Key methodological features included:

• All countermeasure subjects received extensive information about the nature of the CQT
• Subjects participated in mock crimes to create genuine deceptive conditions
• Professional field techniques were employed during examinations
• Standard polygraph instrumentation measured cardiovascular, skin conductance, and respiratory responses

Results & Key Findings

Experiment I showed no significant effects for countermeasures, suggesting that brief training with single techniques was insufficient. However, Experiment II revealed dramatically different outcomes that would fundamentally challenge polygraph validity assumptions.

Countermeasure subjects in Experiment II produced 47% false negative outcomes compared to no false negatives for guilty control subjects. This finding demonstrated that with adequate training, nearly half of guilty individuals could successfully evade detection.

Critical findings included:

• False negative outcomes occurred when subjects produced physiological responses that were larger to control questions than to relevant questions
• The countermeasures worked by augmenting physiological arousal during control questions, thereby obscuring the differential reactivity pattern examiners rely upon
• The study focused on overall effects of countermeasures use without determining whether specific countermeasures led to increased reactions to comparison questions

The physiological data revealed that cardiovascular measures were particularly susceptible to countermeasure manipulation, while skin conductance responses showed relative stability. This pattern suggested that different physiological channels exhibited varying degrees of vulnerability to deliberate manipulation.

Discussion & Significance

This research fundamentally altered the landscape of polygraph science by providing the first systematic evidence that the Control Question Test could be defeated through simple physical countermeasures. A later 1994 study citing this work reported that 60% of decisions were incorrect when subjects had been trained to unobtrusively bite their tongues and press their toes to the floor when control questions were presented, demonstrating the profound impact of these techniques.

The study's implications extended far beyond academic interest. The National Research Council's 2003 review noted that training subjects in physical countermeasures can substantially decrease the likelihood that deceptive subjects will be detected by the polygraph. This finding raised serious questions about polygraph use in high-stakes contexts like national security screening and criminal investigations.

Perhaps equally significant was the dual finding regarding detectability. While countermeasures proved effective at defeating tests, the research also suggested that countermeasure use produced partially detectable patterns in the physiological data. Later work by Honts and colleagues suggests that polygraph examiners do a poor job in detecting countermeasures, indicating that theoretical detectability did not translate into practical countermeasure identification by human examiners.

Limitations & Considerations

Several important limitations to the countermeasures research are worth noting. First, all of the studies have involved mock crimes and most use experimenters or research assistants as polygraph examiners. This raises questions about external validity—whether laboratory findings generalize to real-world high-stakes examinations where both motivation and consequences differ substantially.

The studies involved very short periods of training, typically only 20-30 minutes of instruction. This suggests that more extensive training or practice might produce even higher success rates for countermeasure users, though it also means that even minimal preparation can compromise test validity.

Additional considerations include:

• The study used undergraduate students rather than populations typical of real polygraph screening contexts
• Incentives in laboratory settings may not match the motivation present in actual criminal or employment situations
• The external validity of this body of research is as much in doubt as the external validity of other laboratory studies of polygraph test accuracy

Practical Applications

For polygraph examiners, this research highlighted a critical vulnerability in the Control Question Test and sparked decades of effort to develop countermeasure detection methods. The findings suggested that examiners should carefully observe examinees during testing and scrutinize physiological data for patterns suggestive of augmentation strategies, though subsequent research showed human detection capabilities remain limited.

For policymakers and consumers of polygraph services, the study provides essential context for evaluating the reliability of polygraph results. The 47% false negative rate in trained countermeasure users represents a profound challenge to test validity, particularly in contexts where examinees may have access to countermeasure information. This research underscores that polygraph results should be interpreted with appropriate caution and never serve as the sole basis for important decisions about employment, security clearances, or criminal justice outcomes.