An Evaluation of Field Techniques in Detection of Deception

Field techniques of detecting deception were evaluated using a mock crime situation. Thirty-six Ss were “guilty” of taking $10, and 36 Ss were “innocent,” A field-type interview was followed by a zone comparison control-question polygraph examination. A Keeler field polygraph was used to record physiology activity, and field (semi-objective) and quantitative evaluations of the charts were made. Those who evaluated the charts were not informed about the “guilt” or “innocence” of each S. Using field evaluations, there were 53% correct. 12% incorrect, and 35% inconclusives. Excluding inconclusives there were 81% correct decision. using quantitative scoring, significant discriination between “guilty” and “innocent” was obtaindd with skin resistance, cardiovascular, and respiration measures, with skin resistance best. Field evaluations also produced significant discrimination for all three measures. Blind evaluations of the charts by 5 additional examiners produced high agreement among examiner decisions and a mean correlation of .86 among total scores. Thus, the effectiveness of commonly used field techniques and equipment in differentiating truth and deception was demonstrated in a laboratory setting.     

Physiological Detection of Deception: Measurement of Responses to Questions and Answers During Countermeasure Maneuvers

Physiological detection of deception (“lie detection”) procedures were evaluated with 24 actors, half of whom were “guilty” of a mock-crime and half were “innocent.” All subjects were trained in the Stanislavsky method of acting and were instructed to use this method to appear innocent on the polygraph test. Two versions of the control question detection of deception test were employed: one in which subjects verbally answered immediately following each question and the other in which they delayed their verbal answer for 8 sec following each question. The delayed answer technique allowed the separate measurement of physiological responses to the questions and the answers. Skin resistance responses, cardiovascular changes, and respiration were recorded and analyzed. Excluding inconclusive results, the overall accuracy of the decisions varied between 78% and 91% depending on the test employed. The principal results were: 1) attempts by guilty subjects to appear innocent were totally ineffective, 2) physiological responses elicited by the questions were more valid indicators of deception and nondeception than were the responses elicited by the verbal answers, and 3) errors occurred more frequently with innocent subjects (between 17% and 25% depending on the measure used) than with guilty subjects (0% with each measure). Variables which may affect the generalizability of these results to the field situation are discussed and suggestions for increasing the generalizability of laboratory findings are made.     

Effectiveness of Techniques and Physiological Measures in the Detection of Deception

Control-question (CQ) and guilty-knowledge (GK) techniques for the detection of deception were studied in a mock theft context. Subjects from the local community received $5 for participation, and both guilty and innocent subjects were motivated with a $10 bonus for a truthful outcome on the polygraph examination. They were instructed to deny the theft when they were examined by experimenters who were blind with respect to their guilt or innocence. Eight physiological channels were recorded. Blind numerical field evaluations with an inconclusive zone produced 94% and 83% correct decisions for two different types of CQ tests and 89% correct decisions for GK tests. Control questions were more effective than guilt-complex questions, and exclusive control questions were more effective than nonexclusive control questions. Behavioral observations were relatively ineffective in differentiating guilty and innocent subjects. Quantitative analyses of the CQ and GK data revealed significant discrimination between guilty and innocent subjects with a variety of electrodermal and cardiovascular measures. The results support the conclusion that certain techniques and physiological measures can be very useful for the detection of deception in a laboratory mock-crime context.     

Alcohol and the Psychophysiological Detection of Deception

Psychophysiological detection of deception examinations were conducted on 40 subjects. Of these, 32 were “guilty” of a mock crime and 8 were innocent. Sixteen guilty subjects committed the crime while intoxicated and the remaining 16 committed the crime sober. These two groups of guilty subjects were subdivided such that half of each group was examined with the polygraph while intoxicated and the other half was examined while sober. Two questioning techniques were used in the examination, a Control Question Test and the Guilty Knowledge Test. Measures of skin resistance, heart rate and respiration were recorded. The principal findings were that alcohol intoxication during the crime reduced detectability with detection scores derived from the measurement of skin resistance responses on the Control Question Test and on the Guilty Knowledge Test. The analyses of guilt/innocent classifications, based on the detection scores, showed these classifications to be affected by alcohol intoxication.     

The role of comparison questions in physiological detection of deception

Comparison questions in physiological detection of deception were studied with 60 “guilty’ and 60 “innocent’ participants in a mock crime experiment. Different types of comparison questions were used in four conditions: relevant–irrelevant (R-I) participants answered only relevant and neutral questions; trivial directed lie participants were instructed to lie to three of the six neutral questions; personal directed lie participants were instructed to lie to personally relevant questions; and probable lie participants received traditional probable lie comparison questions. Respiration, cardiovascular, vasomotor, and electrodermal activity were recorded. Manipulation of the comparison questions produced different patterns of physiological responses for innocent but not for guilty participants. The R-I test produced an unacceptable rate of false positive decisions.     

Temperature effects on polygraph detection of concealed information

Thermoregulatory influences on electrodermal and cardiovascular activity may interfere with the detection of concealed information using a polygraph. This possibility was assessed by means of a mock terrorism scenario. Seventy‐two participants were assigned to either a guilty or an innocent role. They were given a polygraph test at one of three ambient temperatures: 10°C, 22°C, or 34°C. Among guilty participants, electrodermal and cardiovascular measures were least effective at 10°C. Electrodermal results were optimal at 22°C, whereas cardiovascular results were optimal at 34°C. Among innocent participants, the effectiveness of these same measures was not affected by ambient temperature. Temperature had no significant impact on respiration results within the guilty or the innocent groups. Taken together, these findings have implications for those who use polygraphs in uncontrolled testing environments.     

New measures improve the accuracy of the directed-lie test when detecting deception using a mock crime

The present study tested the accuracy of probable-lie and directed-lie polygraph tests. One hundred and twenty men and women were recruited from the general community and paid $30 to participate in a mock crime experiment. Equal numbers of males and females were assigned to either the guilty or innocent condition with equal numbers in each group receiving either a probable-lie or a directed-lie polygraph test resulting in a 2 x 2 design with two experimental factors (test type and deceptive condition). Half of the participants were guilty and half were innocent of committing a mock theft of $20 from a purse. All participants were paid a $50 bonus if they could convince the polygraph examiner that they were innocent. There were no significant differences in decision accuracy between probable-lie and directed-lie tests, but respiration measures were more diagnostic for the probable-lie test. New physiological measures, skin potential excursion and a new respiratory measure improved the accuracy of the directed-lie test such that 86% of the innocent participants and 93% of the guilty participants were correctly classified.     

Innocence, Information, and the Guilty Knowledge Test in the Detection of Deception

The purpose of this detection of deception experiment was to study the assumption of the Guilty Knowledge Test that subjects with guilty knowledge will be classed as guilty by the test regardless of their actual guilt or innocence. Prior to a polygraph examination, three groups of innocent subjects were given the same crime-relevant information as members of a group guilty of a mock crime. These innocent subjects either witnessed the crime, were told the crime details, or carried out innocent activities involving crime-relevant information. An additional group of innocent subjects had no crime-relevant information. Analysis of the Guilty Knowledge Test results showed that the detection scores of guilty subjects were higher than those in any of the innocent groups. In fact, with the exception of the innocent activities group, the innocent informed subjects did not differ from those in the uninformed group. The major conclusion is that subjects may have crime-relevant information and not be classed, based on the detection scores, as guilty.     

Effects of Level of Socialization on Electrodermal Detection of Deception

Fifteen college students attempted to deceive a professional polygraph examiner, while 15 others who had nothing to hide also submitted to the examination. The examiner was blind as to whether each subject was deceptive or truthful. Using the skin conductance response (SCR), significant discrimination was made between deceptive and truthful subjects with both “guilty person” and “guilty knowledge” polygraph tests. On both types of test, however, subjects who were not detected were significantly less socialized (Socialization Scale of the California Psychological Inventory) than those who were detected. This reduced susceptibility to detection was mediated by a reduced SCR to deception among low-socialization subjects. Among innocent subjects the highly socialized were more responsive electrodermally throughout the test, leading some of them to be misclassified as deceptive on at least one test. Implications of the results for both detection of deception and the construct of socialization are discussed.     

Alcohol and the physiological detection of deception: Arousal and memory influences

Eighty male volunteers participated in an analogue study of the effects of alcohol intoxication at the time of a crime on the physiological detection of deception using control question and guilty knowledge techniques. Sixty-four of the subjects committed a mock crime and half of these were intoxicated during the crime. Sixteen subjects committed no crime and served as innocent controls. We found that intoxication at the time of the crime had no significant effect on polygraph test outcomes, although it did affect anticipatory arousal before the crime and subsequent memory for crime details. Manipulations designed to influence memory for crime details and arousal during the crime had differential effects for the two polygraph tests. On the guilty knowledge test, primed subjects who rehearsed specific details following the crime were more detectable than unprimed subjects. On the control question test, primed subjects were also more detectable, but only when arousal during the crime was high.     

Mock crime application of the Complex Trial Protocol (CTP) P300‐based concealed information test

The Complex Trial Protocol (CTP), was shown to be an improvement over the previous “three stimulus” P300‐based concealed information tests (CITs). Not only was it highly accurate with autobiographical information but was also resistant to the use of countermeasures (CMs). The current study applied the CTP to the detection of incidentally acquired information in a mock crime scenario. In previous “three stimulus” mock crime studies utilizing P300‐based CITs, participants memorized a guilty knowledge item(s). Special care was taken in the current study to ensure that participants' knowledge of the guilty item in the mock crime was obtained only during the commission of the act in order to bolster ecological validity. Overall, 92% of all participants in guilty, innocent, and countermeasure conditions were correctly classified. CM use was again indexed by reaction times (RTs).     

A Comparison of Field and Laboratory Polygraphs in the Detection of Deception

This study compared the effectiveness of field and laboratory polygraphs in discriminating guilty and innocent subjects tested using the Control Question Technique (CQT). Subjects were 48 prisoners examined regarding a mock theft in a peer threat context; physiological responses were recorded simultaneously on a Lafayette field polygraph and a Sensor Medics laboratory polygraph. Overall hit rates were essentially the same whether classifications were based on quantitative measures from the laboratory polygraph or on numerical scores from the field polygraph (i.e., 73% and 79%, respectively), and in both cases the best discriminating measures were electrodermal activity and indices of respiration suppression. Further analyses revealed that errors of classification were mostly due to the failure of the available measures to differentiate between relevant and control questions for innocent subjects. These results indicate that the CQT is susceptible to false positive errors when subjects are tested under field-like circumstances, a problem that is not likely to be eliminated by refinements in instrumentation and scoring.     

GKT原理的模拟犯罪测试范式实验研究

目的:本实验旨在以实际犯罪较接近的实验场景验证GKT的测谎机制,并探讨其对罪犯以及其他嫌疑人的判定有效性。方法:以72名健康大学生为被试,让被试在模拟犯罪的背景下采用三种包含不同说谎和认知成分的回答方式进行测谎测试,采用Limestone测谎仪测量被试皮肤电反应。结果:回答方式与角色两因子在判定分数上的主效应均显著,交互作用不显著。结论:在模拟犯罪测试范式下,GKT模式中认知与说谎机制是共存的,其中认知成分不占主要地位,说谎成分占主要地位,GKT模式无法兼顾有效地判定"犯罪"和"知情无辜"角色,需进一步改进。     

Salience of Guilty Knowledge Test items affects accuracy in realistic mock crimes.

Guilty Knowledge Test measuring electrodermal reactions was carried out in order to investigate the quality of different questions and the validity of the test in a situation that resembled a true crime. Fifty participants were randomly assigned to commit one of two realistic mock crimes, and were later tested with GKTs concerning both the crime they had enacted and the one they had no knowledge of. Different scoring systems (SCRs and peak amplitudes as well as raw and standardised scores) were employed and compared when analyzing the results. Although there were some false positives, the test was able to differentiate between the groups of guilty and innocent participants. With the best scoring systems, the test was able to classify up to 84% of the innocent and up to 76% of the guilty correctly according to a logistic regression analysis. ROC areas reflecting these same results reached values above .80. Questions on matters that demanded the participants' attention and were easier to remember had better discriminative power. With nearly all scoring methods, there was a significant interaction between the salience of the relevant items and the guilt of the participants. Participants reacted more strongly to salient relevant items when they were guilty, while no different reactions were observed for the non-salient items between guilty and innocent participants. It is suggested that, although the Guilty Knowledge Test appears to be a valid measure of guilty knowledge even in crimes that are close to real crimes, the principles on which guilty knowledge test questions are constructed should be more clearly specified.     

The impact of prior knowledge from participant instructions in a mock crime P300 Concealed Information Test

In P300-Concealed Information Tests used with mock crime scenarios, the amount of detail revealed to a participant prior to the commission of the mock crime can have a serious impact on a study's validity. We predicted that exposure to crime details through instructions would bias detection rates toward enhanced sensitivity. In a 2 × 2 factorial design, participants were either informed (through mock crime instructions) or naïve as to the identity of a to-be-stolen item, and then either committed (guilty) or did not commit (innocent) the crime. Results showed that prior knowledge of the stolen item was sufficient to cause 69% of innocent–informed participants to be incorrectly classified as guilty. Further, we found a trend toward enhanced detection rate for guilty–informed participants over guilty–naïve participants. Results suggest that revealing details to participants through instructions biases detection rates in the P300-CIT toward enhanced sensitivity.     

Detecting Concealed Information Using Functional Near-Infrared Spectroscopy

The present study focused on the potential application of fNIRS in the detection of concealed information. Participants either committed a mock crime or not and then were presented with a randomized series of probes (crime-related information) and irrelevants (crime-irrelevant information) in a standard concealed information test (CIT). Participants in the guilty group were instructed to conceal crime-related information they obtained from the mock crime, thus making deceptive response to the probes. Meanwhile, their brain activity to probes and irrelevants was recorded by functional near-infrared spectroscopy (fNIRS). At the group level, we found that probe items were associated with longer reaction times and greater activity in bilateral dorsolateral prefrontal cortex and supplementary motor cortex than irrelevant items in the guilty group, but not in the innocent group. These findings provided evidence on neural correlates of recognition during a CIT. Finally, on the basis of the activity in bilateral dorsolateral prefrontal cortex and supplementary motor cortex, the correct classification of guilty versus innocent participants was approximately 75 % and the combination of fNIRS and reaction time measures yielded a better classification rate of 83.3 %. These findings illustrate the feasibility and promise of using fNIRS to detect concealed information.     

Psychophysiological and vocal measures in the detection of guilty knowledge.

The Guilty Knowledge Test (GKT) and its variant, the Guilty Actions Test (GAT), are both psychophysiological questioning techniques aiming to detect guilty knowledge of suspects or witnesses in criminal and forensic cases. Using a GAT, this study examined the validity of various physiological and vocal measures for the identification of guilty and innocent participants in a mock crime paradigm. Electrodermal, respiratory, and cardiovascular measures successfully differentiated between the two groups. A logistic regression model based on these variables achieved hit rates of above 90%. In contrast to these results, the vocal measures provided by the computerized voice stress analysis system TrusterPro were shown to be invalid for the detection of guilty knowledge.     

Psychophysiological and behavioral measures for detecting concealed information: the role of memory for crime details

This study examined the role of memory for crime details in detecting concealed information using the electrodermal measure, Symptom Validity Test, and Number Guessing Test. Participants were randomly assigned to three groups: guilty, who committed a mock theft; informed-innocents, who were exposed to crime-relevant items; and uninformed-innocents, who had no crime-relevant information. Participants were tested immediately or 1 week later. Results showed (a) all tests detected the guilty in the immediate condition, and combining the tests improved detection efficiency; (b) tests' efficiency declined in the delayed condition, mainly for peripheral details; (c) no distinction between guilty and informed innocents was possible in the immediate, yet some distinction emerged in the delayed condition. These findings suggest that, while time delay may somewhat reduce the ability to detect the guilty, it also diminishes the danger of accusing informed-innocents.     

Influence of countermeasures on the validity of the Concealed Information Test

The Concealed Information Test (CIT) is a psychophysiological technique that allows for detecting crime‐related knowledge. Usually, autonomic response measures are used for this purpose, but ocular measures have also been proposed recently. Prior studies reported heterogeneous results for the usage of countermeasures (CM) to corrupt the CIT's validity, depending on the CM technique and the dependent measure. The current study systematically compared the application of physical and mental CM on autonomic and ocular measures during the CIT. Sixty participants committed a mock crime and were assigned to one of three guilty conditions: standard guilty (without CM), physical CM, or mental CM. An additional group of 20 innocents was investigated with the same CIT to calculate validity estimates. Electrodermal responses were more vulnerable for CM usage compared to heart rate and respiration, and physical CM were more effective than mental CM. Independent of CM usage, a combined score of autonomic responses enabled a valid differentiation between guilty and innocent examinees. Fixations and blinks also allowed for detecting crime‐related knowledge, but these measures were more affected by CM application than autonomic responses. The current study delivered further evidence that CM differentially impact physiological and ocular responses in the CIT. Whereas individual data channels were strongly affected by CM usage, a combination of different response measures yielded a relatively stable differentiation of guilty and innocent examinees when mental CM were used. These findings are especially relevant for field applications and might inspire future studies to detect or prevent CM usage in CIT examinations.     

Covert respiration measures for the detection of concealed information

A mock-theft experiment was designed to assess the efficiency of two covert respiration measures in detection of concealed information. The covert measures were further compared with three standard measures typically used for the detection of concealed knowledge (electrodermal, respiration and finger pulse measures). Results revealed that the covert respiration measures produced good discrimination between "guilty" (participants possessing concealed knowledge) and "innocent" participants. One of the covert measures produced detection efficiency that was similar to that of the standard respiration and finger pulse measures, but less than the electrodermal measure.