Psychopathy and Polygraph Detection of Deception in a Prison Population

Study of 48 inmates testing CQT effectiveness with psychopathic individuals, finding no accuracy difference between psychopaths and non-psychopaths.

Prison study testing 48 inmates (half scoring high on psychopathy measures) with CQT.

Raskin and Hare tested 48 inmates — half high on psychopathy measures — and found overall 88% accuracy with only 4% errors and 8% inconclusive. Crucially, no significant differences emerged between psychopaths and non-psychopaths, countering the persistent claim that psychopaths can easily defeat the polygraph.

The finding that psychopaths are as detectable as non-psychopaths undermines a common criticism and supports CQT use in forensic settings where psychopathic examinees are common.

Background & Context

The notion that psychopaths can easily "beat" the polygraph has persisted throughout the history of deception detection, fueled by characterizations of psychopaths as fearless, emotionally shallow manipulators immune to the anxieties that drive physiological responses. This 1978 study by David Raskin and Robert Hare directly challenged this assumption by using rigorous diagnostic procedures to identify psychopaths and conducting polygraph tests with an experienced examiner using field procedures.

Published in the journal Psychophysiology, the research addressed a critical gap in polygraph science at a time when the validity of the Control Question Test (CQT) in criminal investigations was under intense scrutiny. The study emerged from collaboration between Raskin, a leading polygraph researcher at the University of Utah, and Hare, whose groundbreaking work on psychopathy assessment was revolutionizing the field of forensic psychology.

The research was conducted at a provincial prison in British Columbia, Canada with 48 male volunteers from the prison population, all convicted felons, with half clinically diagnosed as psychopathic (sociopathic). This was among the first controlled investigations to test whether individuals high in psychopathic traits could evade detection when lying during standard polygraph examinations.

Research Design & Methodology

The study involved 24 psychopathic and 24 nonpsychopathic male prison inmates, with equal numbers of "guilty" and "innocent" subjects tested by experienced professional polygraphers regarding their involvement in a mock theft using standard control question procedures. Participants were carefully selected using reliable psychopathy assessments, ensuring clear diagnostic differentiation between groups.

The experimental paradigm involved a mock crime scenario where half the participants committed a simulated theft while the other half remained innocent. All subjects then underwent standard Control Question Test (CQT) polygraph examinations conducted by experienced field examiners. The testing followed operational procedures used in actual criminal investigations, measuring multiple physiological channels including electrodermal activity, cardiovascular responses, and respiration patterns.

Key methodological features included:

• Rigorous diagnostic classification using standardized psychopathy assessment tools
• Balanced design with equal numbers of psychopaths/non-psychopaths and guilty/innocent subjects
• Field-realistic testing conditions using experienced professional polygraph examiners
• Numerical scoring system for objective evaluation of physiological data

Results & Key Findings

Excluding inconclusive test results, the overall hit rate for psychopathic and nonpsychopathic prisoners was 95.5% with 0% of guilty subjects incorrectly classified and only 9.5% of innocent subjects misidentified. This represented remarkably high accuracy that contradicted prevailing assumptions about psychopaths and polygraph testing.

The headline finding was unequivocal: psychopaths were detected just as easily as non-psychopaths. Imprisoned psychopaths who committed a mock theft could be easily detected using the control question test, and guilty psychopaths were detected just as easily as guilty nonpsychopaths, with 87% of guilty subjects correctly identified excluding inconclusives. There were no significant differences in detection accuracy between the two diagnostic groups.

Specific performance metrics included:

• Overall accuracy: 95.5% when inconclusive results were excluded
• Guilty detection: 100% correct classification across both groups
• Innocent accuracy: 91% for truthful subjects
• No psychopathy effect: Diagnostic status did not predict test outcomes

Discussion & Significance

The findings represented a paradigm shift in understanding psychopathy and deception detection. The common belief in law enforcement, judicial, and polygraph arenas that the psychopath's deception is invisible to the polygraph was contradicted by the relatively limited research evidence. This study provided empirical evidence that psychopaths produce detectable physiological responses to deception despite their interpersonal manipulation skills and emotional deficits.

The results suggested that whatever psychological mechanisms underlie successful CQT detection—whether anxiety about detection, concern about consequences, or cognitive effort associated with deception—they operate similarly in psychopaths and non-psychopaths when tested under controlled conditions. This was theoretically important because it indicated that the affective and autonomic differences observed in psychopaths in other contexts do not translate into an ability to defeat polygraph examinations.

When considering the use of polygraphy in a forensic setting, the question of psychopathy is often raised, but what evidence there is indicates that psychopaths respond to polygraph testing in a similar manner to other individuals. The study's high accuracy rates provided support for the use of CQT in criminal investigations even when dealing with populations likely to include individuals with psychopathic traits.

Limitations & Considerations

The study was later challenged on grounds that the polygraph testing situation lacked a realistic threat component and the examiner's decisions were not based on blind chart analyses. Critic David Lykken argued that the mock crime paradigm failed to capture the high-stakes motivational context of actual criminal investigations, potentially limiting generalizability of the findings.

Additional methodological considerations include:

• Use of simulated crime rather than actual criminal investigations with real consequences
• Potential examiner bias from non-blind chart evaluation
• Sample drawn from a single prison population in Canada
• Relatively small sample size (24 per diagnostic group)
• Limited information about the specific psychopathy assessment criteria used

A constructive replication of the Raskin and Hare study was later carried out by Patrick and Iacono in which subjects were tested regarding a mock theft under conditions of threat rather than reward, addressing some of these criticisms while generally confirming the core finding that psychopaths could be detected.

Practical Applications

The research has important implications for forensic polygraph practice. Examiners can approach testing of individuals suspected or known to have psychopathic traits with confidence that the standard CQT procedures remain effective. The persistent myth that psychopaths can easily defeat the polygraph should not deter use of the technique in criminal investigations, correctional settings, or other forensic contexts where such individuals are commonly encountered.

The finding that psychopaths are no more or less likely to wrongly 'pass' the test means that polygraph results should be interpreted using the same evidentiary standards regardless of the examinee's personality characteristics. However, examiners should remain aware that individual case outcomes depend on proper technique, adequate pretest procedures, and appropriate question construction rather than assumptions about an examinee's psychological makeup.