Personality dimensions predict psychophysiological responses in the Concealed Information Test

Zvi and Elaad (2016) conducted the first study examining how Big Five personality dimensions and locus of control influence physiological responses in the Concealed Information Test. One hundred twenty students committed a mock theft and completed the Guilty Actions Test while personality and physiological measures were recorded. Results showed introversion predicted enhanced skin conductance responses to critical items during initial presentations, while extraversion was linked to sustained cardiovascular responses reflecting deliberate processing.

Mock crime laboratory study with 120 undergraduate participants who completed Big Five and locus of control questionnaires, committed a mock theft, then underwent Guilty Actions Test with repeated question presentations. Three physiological measures (SCR, FPWL, RLL) were recorded to distinguish spontaneous from deliberate information processing.

Background & Context

The Concealed Information Test (CIT) has long been regarded as one of the most scientifically validated polygraph methods, relying on the principle that crime-relevant information produces distinct physiological responses. Yet despite decades of research, a critical gap remained: no study had examined how fundamental personality dimensions might influence an examinee's physiological reactivity during CIT testing.

Understanding individual differences is crucial for polygraph accuracy. The CIT is largely based on orienting response (OR) theory, which holds that novel, unexpected, or personally significant stimuli trigger distinct behavioral and physiological responses. However, emerging research has challenged pure OR theory, suggesting that response inhibition and deliberate arousal suppression may also drive CIT responses, particularly in respiration and cardiovascular measures.

This groundbreaking study by Zvi and Elaad represents the first systematic investigation of how the Big Five personality traits and locus of control affect CIT outcomes, addressing a fundamental question about whether personality moderates the test's detection efficiency.

Research Design & Methodology

One hundred and twenty undergraduate students completed Big Five personality questionnaires and locus of control measures, then were instructed to commit a mock theft. They were subsequently tested using the Guilty Actions Test (GAT), a modified version of the CIT.

The experimental protocol employed several key design features:

• Six sets of questions were presented, with each set repeated twice to examine both spontaneous (first presentation) and deliberate (second presentation) information processing
• Three physiological measures were recorded: skin conductance response (SCR) amplitude, finger pulse waveform length (FPWL), and respiration line length (RLL)
• Participants completed validated personality assessments measuring extraversion, neuroticism, openness, agreeableness, conscientiousness, and locus of control
• The GAT format ensured guilty participants actively lied when responding to critical items

The study distinguished between spontaneous processing (initial orienting responses) and deliberate processing (sustained attention and cognitive effort over repeated presentations), allowing researchers to isolate how personality influences different stages of information concealment.

Results & Key Findings

Introversion predicted enhanced Skin Conductance Responses (SCRs) to critical items only for the first repetition of the first three questions, which was explained by sensitivity to orienting responses. This finding reveals that introverts show stronger initial physiological reactions to crime-relevant information.

In contrast, extraversion was linked to Finger Pulse Waveform Length (FPWL) responses to the first repetition of the first three questions, explained by extended and more deliberate information processing due to increased interest in the experiment. The key findings included:

• Introversion effects were time-limited: The enhanced SCR responses disappeared after the initial questions, suggesting introverts' orienting advantage is restricted to novel stimuli
• Extraversion sustained engagement: Extraverts maintained physiological responsivity longer, likely due to greater task motivation and interest
• Different measures reflected different mechanisms: SCR captured orienting processes while FPWL reflected deliberate cognitive engagement
• Internal locus of control triggered readiness to cope, as indicated by enhanced skin conductance level

This study was the first to demonstrate that Big-Five dimensions and locus of control may affect CIT responsivity in general and responses to critical items in particular.

Discussion & Significance

The findings reveal that different personality dimensions express themselves differently in spontaneous versus deliberate processing of concealed information. Introverts' enhanced initial SCR responses align with established personality research showing introverts are more sensitive to stimulation and arousal. Their rapid habituation after the first few questions suggests they may be easier to detect early in a CIT examination.

Conversely, extraverts' sustained FPWL responses suggest they remain engaged and cognitively active throughout testing. This pattern likely reflects extraverts' greater tolerance for and interest in social-evaluative situations. The distinction between spontaneous (orienting-driven) and deliberate (cognitive-effort-driven) processing offers a more nuanced understanding of CIT mechanisms than pure orienting response theory provides.

The study's implications extend beyond theoretical understanding. The authors note that further studies should focus on how personality and physiological responses are related, suggesting potential for personality-adjusted scoring algorithms or examiner training to account for individual differences. The findings also support emerging theories that multiple mechanisms—orienting, response inhibition, and cognitive load—operate simultaneously during CIT testing.

Limitations & Considerations

The study employed a laboratory mock-crime paradigm with undergraduate student participants, which may not fully replicate the high-stakes emotional context of real criminal investigations. The personality effects observed were specific to certain question repetitions and physiological channels, suggesting the relationships are complex and context-dependent.

Additionally, the study examined only guilty participants (all of whom had committed the mock theft), without comparison to informed innocent examinees. This design limits conclusions about whether personality moderates the test's ability to distinguish guilty from knowledgeable-but-innocent individuals—a critical question for field applications. The relatively small sample size (120 participants) may also limit power to detect subtle personality interactions.

The Big Five model, while comprehensive, may not capture all personality dimensions relevant to deception and concealment. Traits like psychopathy, Machiavellianism, or narcissism—examined in subsequent research by these authors—may prove equally or more predictive of CIT performance.

Practical Applications

This research suggests polygraph examiners should consider personality factors when interpreting test results. Introverts may appear more responsive early in testing but habituate quickly, while extraverts maintain engagement throughout. Examiners might benefit from extended testing protocols for extraverted examinees or placing critical questions strategically early for introverts.

The findings also have implications for screening and personnel security contexts, where personality assessments are often already administered. Combining personality data with physiological testing could improve detection accuracy and reduce false positives. For consumers and defendants, this research underscores that polygraph results reflect not just deception but individual psychological differences—a consideration relevant to legal admissibility debates and informed consent processes.