Effects of mental countermeasures on psychophysiological detection in the guilty knowledge test

This 1991 study examined how mental countermeasures affect detection in the Concealed Information Test using two experiments with 3x2 factorial designs. Paradoxically, item-specific dissociation strategies increased detection rates, while continuous dissociation throughout testing decreased detection efficiency.

Two experiments employed a 3x2 between-subjects factorial design comparing item-specific dissociation, continuous dissociation, and control conditions across high and low attention conditions in both field and standard laboratory settings using electrodermal measures.

Elaad and Ben-Shakhar investigated how mental countermeasures—specifically dissociation techniques—could affect the Concealed Information Test, addressing a critical vulnerability of the CIT to deception strategies. Using a factorial design across field and laboratory contexts, they compared item-specific dissociation, continuous dissociation, and control conditions at high and low attention levels. Results showed that attempting to mentally dissociate from individual relevant items paradoxically enhanced detection accuracy, while maintaining continuous dissociation throughout reduced detection efficiency. These effects were consistent across attention conditions and settings, with stronger patterns in the field experiment where baseline detection was high.

The study demonstrates that understanding countermeasure mechanisms is essential for improving CIT reliability in real-world forensic applications. The counterintuitive finding that some mental strategies backfire while others succeed has important implications for both examiner training and the interpretation of CIT results when countermeasures may be employed.

Background & Context

The vulnerability of polygraph testing to countermeasures has been a persistent concern in psychophysiological detection of deception. This 1991 study by Elaad and Ben-Shakhar focused on the effects of mental countermeasures on psychophysiological detection in a guilty knowledge paradigm, addressing a critical gap in understanding how cognitive strategies might defeat the Concealed Information Test (CIT), then called the Guilty Knowledge Test (GKT).

Unlike physical countermeasures that involve observable behaviors like toe-pressing or tongue-biting, mental countermeasures operate through covert cognitive processes. This research was groundbreaking because it systematically examined whether guilty examinees could use internal mental strategies—specifically dissociation techniques—to evade detection. The study's importance extended beyond theoretical concerns, as the vulnerability of the CIT to countermeasures (attempts of knowledgeable, guilty individuals to distort their physiological reactions and avoid detection) is one of the test's key limitations.

Research Design & Methodology

Two experiments utilizing a 3 x 2 between-subjects factorial design were conducted. The research employed a sophisticated approach that tested countermeasure strategies in both laboratory and field settings, enhancing ecological validity.

Two types of mental countermeasures were examined: specific dissociations from the relevant stimulus and continuous dissociation throughout the entire test, as well as a control-no countermeasure condition. Each group was further subdivided into two conditions—a high attention condition created by motivational instructions and a deceptive verbal response to the relevant question; and a low attention condition in which no motivational instructions were provided and no verbal response was required.

Key design elements included:

• Three countermeasure conditions: item-specific dissociation, continuous dissociation, and no-countermeasure control
• Two attention levels: high motivation with verbal deception vs. low motivation without verbal response
• Dual experimental settings: field setup and standard laboratory with experimental equipment
• Electrodermal measurement: primary physiological indicator of detection

Results & Key Findings

The study revealed a paradoxical pattern: item-specific countermeasures tended to increase psychophysiological detection, whereas the continuous dissociations tended to decrease detection efficiencies. This counterintuitive finding demonstrated that not all countermeasure strategies are equally effective.

The pattern was consistent across attention conditions and experiments but it was stronger in the field experiment where overall detection efficiency was relatively high. Key findings included:

• Specific dissociation backfired: Attempting to mentally dissociate from individual relevant items actually enhanced detection rather than defeating it
• Continuous dissociation showed promise: Maintaining dissociation throughout the entire test reduced detection efficiency for guilty examinees
• Attention factor remained significant: The results replicated previous findings and revealed a significant effect for the attention factor
• Consistent cross-setting effects: The countermeasure pattern held across both field and laboratory contexts

Discussion & Significance

This research made a seminal contribution to understanding countermeasure effectiveness in the CIT. The paradoxical finding that item-specific countermeasures increased detection suggests that focusing attention on relevant items—even with the intent to dissociate—may inadvertently enhance the orienting response that underlies CIT detection. The guilty examinee's attempt to mentally "do something" when the critical item appears may actually amplify the very physiological reactions they seek to suppress.

The relative success of continuous dissociation strategies highlighted a genuine vulnerability in the CIT. By maintaining a dissociated mental state throughout the entire examination rather than selectively targeting critical items, examinees could reduce the differential responding that forms the basis of CIT detection. This finding has influenced subsequent countermeasure research and the development of counter-countermeasure techniques.

The study's replication across field and laboratory settings strengthened confidence in the findings and demonstrated their applicability beyond controlled experimental conditions. The stronger effects observed in the field setting, where detection was already more efficient, suggested that real-world factors may modulate countermeasure effectiveness in complex ways.

Limitations & Considerations

While the study provided valuable insights, several limitations warrant consideration. The research employed simulated scenarios rather than actual criminal investigations, which may not fully capture the psychological dynamics of real deception. Guilty participants were explicitly trained in countermeasure techniques, whereas real-world examinees typically lack such systematic instruction—though this limitation actually makes the findings more conservative regarding CIT vulnerability.

The study focused exclusively on electrodermal measures, leaving open questions about whether similar patterns would emerge with cardiovascular or respiratory channels. Additionally, the specific content and instructions for the dissociation strategies were not fully detailed in available sources, making precise replication challenging. The interaction between countermeasure type and individual differences in imagery ability or dissociative capacity was not explored.

Practical Applications

For polygraph examiners, this research underscores the importance of recognizing that countermeasure attempts may actually be detectable. An examinee employing item-specific mental strategies may show enhanced rather than suppressed responding, potentially signaling countermeasure use. This awareness should inform both test administration and chart interpretation.

The finding that continuous dissociation can reduce detection efficiency has driven the development of counter-countermeasure approaches, including the use of covert physiological measures and modified question presentation formats. Examiners should be alert to examinees who appear mentally distant or disengaged throughout testing, as this may indicate continuous dissociation attempts. The research also supports the value of multi-channel recording, as different physiological measures may show varying susceptibility to mental countermeasures.