• Korean Journal of Culture and Social Issue
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• v.11 no.4
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• pp.1-22
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• 2005

Purposes of this study was as following; What differences do subjective indicators of deception detection according to high and low stake situations? Does groups difference appear in beliefs about deception cues? Is what differences between objective indicators and subjective indicators of deceptions? Participants of this study were consisted of university students, prison officers, prisoners. They completed a questionnaire concerning beliefs about 21 verbal and nonverbal behaviours in high/low-stake situations. For each behaviour, they were asked to rate on a seven-point scale how are these behaviours changed comparing to normal times. The results were that subjective indicators of deception were no differences between high-stake and low-stake situations, and no differences among groups. Also, it appeared that the subjective indicators of deception were substantly different from the objective indicators of deception.

• Korean Journal of Culture and Social Issue
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• v.12 no.2
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• pp.101-114
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• 2006

This study was examined the effective nonverbal behavior cues of detecting suspects' lies in the investigation scene. In order to search the suspects who drank the alcohol liquor without a permission, 18 soldiers were interviewed. 8 solders had drunken alcohol and had lied when was asked(lie group). The other 10 soldiers hadn't drunken alcohol and had told the truth(truth group). The mean frequencies of nonverbal behaviors were compared lie group with truth group. The following behaviors were measured by frequency: vocal characteristics (high pitch of voice, speech hesitations, speech error, frequency of pauses, period of pauses, latency period), facial characteristics (gaze, smile, touching face, blinking, facial micro-expression), body movement (illustrators, hand and finger movement, leg and foot movement, head movement, trunk movement, shifting position). As results, this study found that deception cues were periods and frequencies of pause, micro-expression, head movements. The lie group had less periods and frequencies of pause, and more micro-expression, head movements than truth group. But, this study didn't found Othello's error cues.

• Korean Journal of Forensic Psychology
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• v.11 no.2
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• pp.155-171
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• 2020

The purpose of this study is to examine the effects of emotional arousal and cognitive load on pupil diameter during a lie detection interview. The guilty group (n = 30) committed a mock crime (i.e., stealing cash) and the innocent group (n = 30) performed a mission (i.e., sending a message) in the research assistant's office. After that, their pupil size was measured using a wearable eye-tracker during the interview. The interview questions were classified with the three cognitive load, three emotional arousal, and three neutral questions. The results indicate that the main effects of group and time were not significant, but the interaction between group and time was significant. It means that when answering cognitive load questions, the guilty group showed larger increase in pupil diameter than the innocent group. The present study suggests that inducing cognitive load is more effective than inducing emotional arousal during an interview when using pupil diameter as an index of deception, and it is expected to improve the accuracy of lie detection.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.17-18
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• 2011

본 논문에서는 일반적으로 뇌파, 호흡운동, 표정변화, 심전도, 산소포화도, 인체의 땀 등을 이용하여 거짓말 탐지를 하는 것을 근간으로 하여 일상생활에서 쉽게 거짓말 탐지를 할 수 있는 시스템을 제작하여 제시한다. 이 거짓말 탐지기 시스템 제작을 통해 생체신호를 스마트폰과 연동함으로써 건강기기의 또 다른 방향을 제시할 것으로 기대된다.

• Korean Journal of Forensic Psychology
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• v.11 no.3
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• pp.349-370
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• 2020

This study was to test the effects of unanticipated questions on the number of general and verifiable details. In addition, the number of verifiable details would discriminate truth-tellers and liars more accurately than the number of general details. In a 2(Veracity: truth vs. lie) X 2(Question type: Expected questions vs. Unexpected questions) mixed-design study, truth tellers(N=40) were asked to visit a cafe on campus and liars(N=40) were told to fabricated a story as if they visited the cafe. Then, participants were interviewed about their trip to the cafe and asked four questions(two anticipated questions: 'report the trip in detail', 'describe the place'; two unanticipated questions: 'recall in reverse order', 'report verifiable details'). Each participant's statements were transcribed and coded by trained graduate students for the number of general details and verifiable details. The results showed that truth-tellers mentioned significantly more general details than liars regardless of the question type. On the contrary, there was no significant difference between liars and truth-tellers in the number of verifiable details. High percentages of truth-tellers(62.5%) and liars(80.0%) were classified correctly based on the number of general details whereas only 45.0% of truth tellers and 62.5% of liars were accurately classified by the number of verifiable details. Liars were found to speak more words when asked to provide verifiable details compared to a general open question, but the number of general details did not seem to increase accordingly. The limitations of this study and future research directions were discussed.

• Korean Journal of Cognitive Science
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• v.27 no.2
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• pp.247-273
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• 2016

Previous studies about lying were mainly executed in pressure situations, such as interviews or crime statements, which made people stressed. This study analyzed deceptive and non-deceptive writings in non-pressure situation through K-LIWC program, in which lies are rarely disclosed and hardly damage the liar even upon disclosure, Also, we compared these results with existing studies on lying. On both writing tasks, there were fewer first-person singular pronouns in deceptive writings than in the non-deceptive writings. The variables indicating cognitive complexity were less used by deceptive writings than by non-deceptive writings in first topic, but in the second topic, more were used by deceptive writings than true writings. In particular, previous studies claim that lies contain more negative emotional words while this report shows that lies in non-pressure situations contains more positive and fewer negative emotional words compared to truth. This finding implies that a situation influences the liar's psychological statement, which changes the contents of the lie.

• Korean Journal of Culture and Social Issue
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• v.14 no.4
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• pp.103-117
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• 2008

The polygraph test administered by the Korean Prosecutors Office for crime investigations customarily uses the score of -12 as the cutoff point separating the subjects who lie from those who tell the truth. The criterion used by the KPO is different from the one (-13) suggested by Backster (1963) who invented the particular method for lie detection. Based on the signal detection theory applied to the real polygraph test data obtained from real crime suspects by the KPO, the present study identified the score of -8 as an optimal criterion resulting in the highest overall accuracy of the polygraph test. The classification of the subjects with the score of -8 as the criterion resulted in the highest accuracy (83.17%) compared with the accuracies of classifications with the Backster's criterion (76.24%) and the KPO's criterion (80.20%). However, the new criterion was also found to result in more false-positive cases. Based on the results from the present study, it was recommended to use the score of -8 as the criterion when the overall accuracy is important but the score of -12 or -13 when avoiding false-positive is more important than securing the overall accuracy.

• Korean Journal of Forensic Psychology
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• v.11 no.1
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• pp.89-115
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• 2020

Traditional deception detection methods had examined the difference of one's autonomic physiological responses through asking crime-related and crime-unrelated questions. There has been a continuing controversy regarding the accuracy and validity of the test, and thus, many researchers were motivated to explore and develop alternative efficient methods of detection in which one of them is known as P300-based Complex Trial Protocol (CTP). The P300-based CTP detects deception through comparing the P300 amplitudes between probe and irrelevant stimuli and is known as a counterstrategy of countermeasures. However, many previous studies have used countermeasures created from Rosenfeld et al.'s work (2008). The present study initially conducted a survey asking open-ended questions about the countermeasure use to acquire participant-oriented countermeasures for the main experiment. Then, the study aimed to evaluate whether the CTP can accurately detect deception even in the use of survey-based countermeasures. We firstly selected a set of participant-oriented countermeasures through survey questions. Then, a total of 50 participants were divided into three groups (innocent, guilty, and countermeasures) and performed the CTP. Those assigned to the countermeasures group covertly performed mental countermeasures during the CTP. The results of P300 amplitude analysis revealed that the guilty group's P300 amplitude of probe stimuli was significantly larger than that of irrelevant stimuli. Countermeasures group also had a significantly larger P300 amplitude for probe stimuli compared to irrelevant stimuli, even in the use of countermeasures. The results of bootstrapped amplitude difference (BAD) showed a detection accuracy rate of 81.25%, 82.35%, 82.35% for the innocent, guilty, and countermeasures groups, respectively. These findings demonstrate that the CTP can obtain a high detection rate in participant-oriented countermeasures and suggest the potential use of the CTP in the field.

• Science of Emotion and Sensibility
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• v.12 no.4
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• pp.557-564
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• 2009

For scoring polygraph charts, the Prosecutors' Office of the Republic of Korea uses a consistency criterion in which an elevated signal on one physiological channel is scored as a deceptive response only if the signal is also elevated on other channels. In the current study, the effects of this scoring criterion on reliability and accuracy (validity) of polygraph scores were assessed. Polygraph tests on 26 suspects were evaluated twice by the same examiners. The examiners used the consistency criterion in the first evaluation. In the second evaluation, the examiners were prevented from using the criterion; the signals from each physiological channel were separated and randomly arranged before they were rescored by the same examiner. Reliability was assessed by the variation among the scores for each suspect. Accuracy was assessed by establishing a standard, based on a Latent Class Analysis model, using the results of polygraph tests on each of 182 additional suspects. Reliability and accuracy were both improved by the use of the consistency criterion which therefore was recommended.

• Science of Emotion and Sensibility
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• v.20 no.3
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• pp.109-118
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• 2017

This study examined the effects of button response to probe and irrelevant stimuli on P300 amplitude and lie detection rate in P300-based concealed information test. Participants underwent the P300-based concealed information test (P300 CIT) in two conditions. In one button condition participants were instructed to press the left mouse button only when the target was present. In two button condition, they were asked to press the left mouse button for target and right button for non-target. The results showed that the response time to target stimulus was not significantly different between the two conditions, and the response time to the probe stimulus was significantly longer than the irrelevant stimulus. The P300 amplitudes for the probe and irrelevant stimulus were all smaller in one button condition compared to two button condition. However, the P300 amplitude difference between the probe stimulus and the irrelevant stimulus did not show a significant difference in the two experimental conditions, and the lie detection rate did not differ significantly between the two conditions. Based on these findings, the effect of button response on P300 CIT with a short inter-stimulus interval was discussed.