The Role of 'Lying' in Psychophysiological Detection

Kugelmass, Lieblich, and Bergman (1967) used a reversed card-test paradigm in which subjects were required to answer 'YES' to all stimuli presented — lying on every trial except the one corresponding to their actually selected item. The study demonstrated that physiological detection occurred at above-chance levels based on the augmented response to the truthful answer, not to the lies, directly challenging the assumption that the act of lying itself drives psychophysiological arousal in deception detection.

Controlled laboratory card/number test with a forced-YES response format; subjects lied on all trials except the one corresponding to their selected item, with galvanic skin response (GSR) used as the primary physiological measure.

This landmark 1967 study by Kugelmass challenged the prevailing theory that lying itself drives physiological arousal in polygraph detection by inverting the standard card test paradigm. Subjects were motivated to deceive but required to answer 'YES' to all questions about card selection, meaning they lied on every trial except when asked about their actual chosen card. Results showed that subjects could be identified at significantly above-chance levels based on their enhanced physiological response when telling the truth about their selected card, not from their responses while lying. This finding was logically incompatible with theories that verbal deception is the causal mechanism underlying psychophysiological detection.

The findings fundamentally challenged the theoretical foundation of polygraph science by demonstrating that physiological arousal patterns are driven by factors other than the act of lying itself, suggesting that recognition or emotional salience of relevant items may be more important than deceptive behavior.

Background & Context

By the mid-1960s, polygraph science was operating under a widely held but largely untested assumption: that the act of lying itself — the deliberate verbal falsehood — was the primary engine driving physiological arousal in deception detection paradigms. This assumption was embedded in the common parlance of calling polygraph instruments "lie detectors," and it shaped both practitioner training and theoretical models of the era.

The conditioned response theory held that relevant questions play the role of conditioned stimuli and evoke in deceptive individuals an emotional and concomitant physiological response with which lying has been associated during acculturation. This framework implied a tight causal link between the verbal act of deception and the resulting autonomic response — a link that Kugelmass, Lieblich, and Bergman set out to directly test.

The 1967 study emerged from an active Israeli research programme exploring the psychophysiological foundations of deception detection. Kugelmass, Lieblich, and Bergman's paper, "The Role of 'Lying' in Psychophysiological Detection," was published in Psychophysiology, Volume 3, pages 312–315, in 1967. Its clever reversal of the standard card-test paradigm gave it an outsized theoretical impact far beyond its brief length.

Research Design & Methodology

The study employed a reversed card test — a modification of one of the most established paradigms in psychophysiological deception research. In the usual card or number test situation, all possible cards (including the one that the subject has selected) are presented as stimuli, a procedure which automatically requires that the subject lie concerning the card he actually selected. Kugelmass and colleagues inverted this logic entirely.

A study by Kugelmass, Lieblich, and Bergman further documents this point, using a card test with subjects motivated to deceive but now requiring them to answer YES each time a tape recording asked whether they had taken a particular card. Thus, if a subject had selected the number 15 and was asked "Did you take the number 17?" he would be required to answer YES — lying. If asked "Did you take the number 12?" he would again say YES — again lying. However, when the subject was asked "Did you take the number 15?" — which he had selected — he would be telling the truth.

Key design elements of the study include:

• Paradigm: Reversed number/card test with forced-YES response format
• Deceptive response: Subjects lied on every trial except the critical (chosen) item
• Truthful response: Only the critical stimulus elicited a truthful "YES" answer
• Primary measure: Galvanic skin response (GSR) / electrodermal activity
• Motivation: Subjects were motivated to deceive, consistent with prior card-test protocols
• Setting: Controlled laboratory experiment conducted in Israel

Results & Key Findings

The core finding was striking: subjects could be identified at significantly above-chance levels — not from their physiological responses to their lies, but from their augmented response when they told the truth. The item the subject genuinely selected produced the largest physiological reaction, even though it was the only moment in the entire procedure when the subject was not lying.

Under these circumstances, subjects motivated to deceive could readily be identified at far greater than chance levels by their augmented physiological response while truthfully answering that they had selected their particular card. This outcome was logically incompatible with the notion that lying, as a verbal act, is the causal mechanism underlying psychophysiological detection.

The key findings can be summarized as follows:

• Detection succeeded even when subjects were lying on all but one trial
• The critical (truthful) stimulus produced the largest GSR response
• Identification accuracy was well above chance using standard card-test evaluation criteria
• The verbal response type (truth vs. lie) was dissociated from physiological arousal magnitude
• Stimulus significance and salience, not verbal deception, drove autonomic differentiation

It is clearly not lying which produces an increased physiological response in this situation, since the subject is required to lie every time except when responding to the critical card. This elegant dissociation constituted one of the clearest early demonstrations that the polygraph is better understood as a significance detector than a lie detector.

Discussion & Significance

The theoretical implications of this study reverberated through decades of polygraph scholarship. This item produces a different response from the others, whether the examinee denies special knowledge about any of the items (i.e., lies about the selected item) or claims special knowledge about all of the items (i.e., lies about all but the selected item). This symmetry demonstrated that the direction of the verbal response is irrelevant — what matters is the psychological significance of the stimulus itself.

The findings provided critical empirical support for what would later be elaborated as arousal theory and related cognitive accounts of detection. The related arousal theory holds that detection occurs because of the differential arousal value of the various stimuli, regardless of whether or not there is associated fear, guilt, or emotion. Kugelmass et al.'s reversed card test was one of the earliest direct experimental demonstrations of this principle.

The study also reinforced the theoretical coherence of the Concealed Information Test (CIT) over guilt-presumptive approaches. Because there is no unique psychophysiological response pattern associated with lying, methods for detecting deception involve comparing physiological responses to different types of questions. Kugelmass et al. had shown empirically, years before this consensus crystallized, that it is the concealed knowledge — not the utterance of a falsehood — that animates the physiological signal.

Limitations & Considerations

As with virtually all laboratory card-test research of the era, several methodological constraints limit the direct generalizability of these findings to field polygraph practice. Key considerations include:

• Ecological validity: A number/card test bears only partial resemblance to the high-stakes criminal or security examination setting
• Sample characteristics: With some exceptions, subjects in these studies tend to be college students, a group that differs markedly from the clients of the "lie detection" experts.
• Consequence asymmetry: Laboratory subjects face no real-world consequences for detection, potentially underestimating motivational effects in actual exams
• Single-channel measurement: Reliance primarily on GSR may not capture the full psychophysiological response profile used in multi-channel field polygraph
• Artifact of forced response: The reversed YES paradigm is artificial — real examinees choose their own response strategy, introducing variability not captured here

It should also be noted that the paper was brief — spanning only four pages — and reporting conventions of the era meant that full statistical tables, effect sizes, and sample demographics were less systematically documented than modern standards require. Nonetheless, its conceptual contribution far outweighed its modest length.

Practical Applications

The practical takeaway from Kugelmass, Lieblich, and Bergman (1967) is foundational: polygraph examiners and consumers should understand that the instrument does not detect lying as such. The physiological signals recorded during a polygraph examination reflect the psychological significance of stimuli to the examinee — which is why properly constructed test formats, such as the Concealed Information Test, place stimulus salience at the center of their design rather than the verbal act of denial.

For practitioners, this finding underscores the importance of question construction and the selection of critical items that are genuinely salient only to a guilty examinee. In the laboratory, one may create a situation that, when seen from the subject's point of view, has many of the elements of the guilty person paradigm, while retaining the structure of the guilty information paradigm in the manner of stimulus presentation and selection of control questions. Understanding that detection flows from stimulus meaning — not verbal behavior — remains essential to both valid test design and the accurate interpretation of polygraph data.