Effects of physical countermeasures on the physiological detection of deception.

In Exp I, 48 undergraduates were divided into 4 groups, 3 of which enacted a mock crime. Two of these guilty groups were trained in the use of a countermeasure, either biting the tongue (pain countermeasure) or pressing the toes against the floor (muscle countermeasure) during the control question zones of the control question test (CQT). All countermeasure Ss were given extensive information about the nature of the CQT. Results show that no significant effects for countermeasures were found. In Exp II, 57 Ss were divided into 3 groups, 2 of which enacted a mock crime, to assess the effects of additional training and concurrent use of both countermeasures. Results show that countermeasure Ss produced 47% false negative outcomes as compared to no false negatives for guilty control Ss. False negative outcomes occurred when Ss were able to produce physiological responses that were larger to control questions than to relevant questions. Findings should be qualified by the possibility that the countermeasure task would be more difficult if the relevant questions dealt with a real crime in an actual investigation. It is concluded that a substantial number of Ss can be trained to defeat a CQT in a laboratory paradigm. (33 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Awareness of crime-relevant information and the Guilty Knowledge Test.

The effects of awareness of crime-relevant information on the detection of deception with the Guilty Knowledge Test were examined. Student Ss were assigned to 1 of 3 groups: a guilty group, members of which committed a mock crime; an innocent group aware of details about the crime; or an innocent group unaware of such information. After following instructions, Ss were tested on the polygraph with a 10-item Guilty Knowledge Test and were offered $20 for an innocent test outcome. Skin resistance response scores of guilty Ss lying about crime-relevant information were higher than the scores of innocent informed Ss, whose scores in turn were higher than those of innocent unaware Ss. This replicated findings of an earlier study in which similar procedures were used and supported the view that Ss aware of crime-relevant information can appear less deceptive than Ss lying about crime-relevant information. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Positions of Truthfully Answered Controls on Control Question Tests With the Polygraph.

Students (N = 120) guilty of a mock crime, innocent and informed, or innocent and uninformed of crime details were examined by polygraph with an altered form of Control Question Test (CQT). Ambiguous, lie-engendering control questions were altered to form clear direct questions answered truthfully. When these control questions were positioned before crime-relevant questions, most guilty and innocent participants were correctly classified. Most participants were classed as guilty when crime-relevant questions were positioned before control questions. Lying to crime-relevant questions in the second position resulted in skin resistance, F(2,108) = 8.2, and blood volume, F(2, 108) = 6.1, responses larger than Orienting Responses to initial control questions. Accurate detection depends on the position of control questions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Use of antianxiety drugs as countermeasures in the detection of guilty knowledge.

To evaluate whether antianxiety drugs enable guilty Ss to appear innocent on polygraph tests, the authors compared the effects of diazepam, meprobamate, and propranolol on the outcome of a guilty knowledge test (GKT). 75 undergraduate students were evenly divided among 1 innocent and 4 guilty groups. Ss in each of the guilty groups received either 1 of the drugs or a placebo prior to the administration of the GKT and after viewing a videotape that depicted a burglary as seen from the perspective of the burglar. The results showed that drug status had no influence on the outcome of the GKT. Innocent Ss who coincidentally obtained high scores on a recognition memory test covering details of the mock crime tended to obtain higher guilt scores on the GKT. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Deception and nondeception in guilty knowledge and guilty actions polygraph tests.

Two polygraph tests, the Guilty Knowledge Test (GKT) and the Guilty Actions Test (GAT), were compared in a laboratory setting. Men (N?=?120) who committed or witnessed a mock crime were required to answer "no"", to repeat items, or to remain silent in response to items on the GKT or the GAT. A monetary reward was promised for appearing innocent on the test. An interaction with scores based on skin resistance responses showed that innocent witnesses tested on the GKT and guilty participants tested with either the GKT or the GAT scored more in the guilt direction than did innocent witnesses tested on the GAT. Furthermore, participants who were required to say "no"" were more reactive to key items than were participants in the silent group. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of feedback of physiological information on responses to innocent associations and guilty knowledge.

Investigated the effects of providing Ss with feedback concerning their physiological responding while they were questioned about (a) innocent associations varying in degree of personal involvement and (b) innocent associations vs guilty knowledge. In Exp I, 48 undergraduates were divided into 3 groups—electrodermal, heart-rate, or no feedback. Ss were then questioned separately about a list of geometric figures, containing one that they had chosen beforehand, and about a list of Social Security numbers, which included their own. Results, based on the relative amplitude of electrodermal responses, indicate that feedback significantly augmented responses to the relevant item as did personal involvement. In Exp II, 26 undergraduates were provided with guilty knowledge about a mock crime while another 26 Ss received innocent associations. Half of each group received electrodermal feedback and half no feedback. Results show significant differences in the responding of guilty and innocent Ss. Feedback increased responding to relevant items in both groups. (5 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A control question test oriented towards students

Control Question Tests were altered for 12 of 24 students who were examined with a polygraph about a mock crime which half of them had committed. The altered tests substituted control questions about students' cheating and plagiarism for the standard questions about crime issues. Responses to the altered tests were compared with those from tests using regular control questions which are usually about criminal issues. All tests were conducted by a professor. Detection scores derived from response magnitudes of skin resistance differed between innocent (M = 2.0) and guilty participants (M = -1.9). Guilt and innocence interacted with the type of test. Those examined with control questions oriented towards students scored as more innocent when actually innocent (M = 4.3) than guilty students examined with the student form (M = -3.0) or the crime form (M = -0.8) of the test and innocent students (M = -0.3) examined with control questions oriented towards crimes. The discussion is augmented by results from a direct analysis of magnitude of scores.     

Mock Jurors' Perceptions of Child Witnesses: The Impact of Judicial Warning.

The present study examined the impact of a judicial warning, witness age, and the method of testimony presentation on mock jurors' perceptions of credibility of witnesses and accused, and on guilty verdicts. The participants were 435 undergraduate university students who listened to an audio-taped summary of a theft trial followed by abbreviated instructions to the jury. Witness age was 7, 10, or 23, the jury warning was either present or absent when witnesses were children, and the testimony by the prosecution eyewitness and accused were either presented or summarized. For the taped testimony conditions, the mock witnesses and the accused read a fact pattern describing the events in the case and were audiotaped as they answered a series of questions, which constituted direct and cross-examination. The testimony of the 7-year-old child, compared to the 10-year-old, was associated with lower cognitive competence and higher suggestibility, but also with higher accuracy of recall (lower mistaken recollection) and lower credibility of accused. The pattern of results for appraisal of the older child was more similar to that of an adult witness. The young adult was judged to be less trustworthy than children of either age. While the presence of a warning had no impact on guilty verdicts when a 7-year-old was a witness, there were fewer guilty verdicts when a witness was 10 years old. Participants also made fewer guilty verdicts when a young adult's testimony, compared to conditions involving child witnesses, was presented, but not when it was summarized. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of altered outcome expectancies stemming from placebo and feedback treatments on the validity of the guilty knowledge technique.

Examined the effect of using placebo and feedback treatments to alter outcome expectancies on the detection efficiency of the guilty knowledge polygraph technique. 270 undergraduates each committed a mock murder, after which the investigator administered a series of 5 lie detector tests to ascertain the facts involved in the simulated murder. Prior to testing, an equal number of male and female Ss were randomly assigned to 1 of 9 treatment groups. The groups consisted of the different treatment combinations produced by pairing 1 of 3 placebo conditions (pass, control, fail) with 1 of 3 feedback conditions (pass, control, fail). Although highly significant sex and feedback effects on outcome expectancies were found, there were no significant main or interaction effects produced by the sex, feedback, or placebo conditions with respect to detection efficiency as measured by a standard guilty knowledge scoring procedure. Results support the detection of deception theories that stress the importance of differential arousal and/or habituation effects associated with relevant and irrelevant stimuli. (25 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The GSR in the detection of guilt.

How accurate is a lie detector in determining guilt? "Forty-nine male college students, after random assortment into four groups, were required to enact one, both, or neither of two mock crimes. All were then given a guilty knowledge test, employing the GSR, which used six standard questions relating to each of the two crimes. A simple, objective, and a priori scoring system was used to determine guilt. Forty-four or 89.8% of the Ss were assigned to their correct group, against a chance expectancy of 25%. Considering the crimes separately, all Ss innocent of a crime were correctly classified, while 44 or 50 interrogations of guilty Ss gave guilty classifications, a total of 93.9% correct classification against a chance expectancy of 50%… . Detection of guilty knowledge… is demonstrably capable of very high validity in those situations where it can be used." (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Appearing Truthful Generalizes Across Different Deception Situations.

The authors investigated whether the ability to appear truthful is specific to deception situations. Male participants were interrogated after they took part in 2 high-stake deception situations, one involving a mock crime and another involving a false opinion. The videotaped interrogations from each situation were shown to independent groups of undergraduate observers. The proportion of observers who judged each participant as truthful in one situation correlated highly with the proportion of observers who judged the same participant as truthful in the other situation. This was not correlated with physiognomy judgments. Follow-up studies revealed that although the participants showed consistency in their facial, body, and paralinguistic behaviors across situations, observers' judgments seemed to be driven only by the consistency of the dynamic facial behaviors. These results are discussed in terms of the evolutionary importance of the face in communication. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of diazepam and methylphenidate on the electrodermal detection of guilty knowledge.

60 19–28 yr old male undergraduates were randomly assigned to 1 of 4 groups in an investigation of the effects of antianxiety (diazepam) and stimulant (methylphenidate) drugs on polygraphic interrogation. Ss assigned to the 3 guilty groups watched a videotape depicting the burglary of an apartment through the eyes of the thief. Each S was asked to imagine that it was he who was committing the crime and was given instructions to encourage his becoming absorbed in the videotape. Ss were given either diazepam, methylphenidate, or placebo capsules before a polygraph examination. Control Ss viewed a videotape depicting scenes from the interior of another apartment (no crime was committed) before being given a polygraph examination. Results show that drug status did not affect the validity of the polygraph examination. Ss who remembered more facts scored significantly more in the guilt direction. (31 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Inadmissible evidence and juror verdicts.

288 mock jurors watched videotapes of a realistic simulated trial and rendered verdicts as individuals before deliberation and as groups after deliberation. In a 3?×?2 design, the trial evidence and judge's instructions were varied. The trial contained inadmissible evidence supporting conviction, inadmissible evidence supporting acquittal, or no inadmissible evidence. The judge's instructions emphasized the importance either of protecting the defendant's due process rights or of reaching an accurate verdict. Jurors who received proacquittal inadmissible evidence were less likely to convict than those who received either proconviction inadmissible evidence or no inadmissible evidence. The conviction rates in the latter 2 conditions did not differ significantly. The variation in judge's instructions had no effect. Paradoxically, jurors who received proconviction inadmissible evidence thought that their verdicts had been influenced by it, whereas those who received proacquittal inadmissible evidence thought that their verdicts has not been influenced by it. Jurors' evaluations of the strength of admissible evidence were not influenced by the presence of inadmissible evidence. (20 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A quantitative review of the Guilty Knowledge Test.

The guilty knowledge polygraph test (GKT; D. T. Lykken, 1959, 1960) is a psychophysiological method of identifying suspects with concealed information about a crime. A meta-analysis of 50 treatment groups drawn from 22 laboratory simulation studies (total N?=?1,247) was conducted to provide a comprehensive estimate of GKT accuracy under controlled conditions. Electrodermal measures correctly identified 76% of participants with concealed knowledge and 83% of those without information. Informed participants were detected at rates significantly in excess of chance, with a mean weighted effect size of .57. Enactment of mock crimes increased the hit rate to 82%. The rates of false-positive error among noninformed treatment groups did not significantly exceed chance. Applications and research directions are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Asymmetric influence in mock jury deliberation: Jurors' bias for leniency.

Investigators have frequently noted a leniency bias in mock jury research, in which deliberation appears to induce greater leniency in criminal mock jurors. One manifestation of this bias, the asymmetry effect, suggests that proacquittal factions are more influential than proconviction factions of comparable size. A meta-analysis indicated that these asymmetry effects are reliable across a variety of experimental contexts. Exp I examined the possibility that the leniency bias is restricted to the typical college-student subject population. The decisions of college-student and community mock jurors in groups beginning deliberation with equal faction sizes (viz., 2:2) were compared. The magnitude of the asymmetry effect did not differ between the two populations. In Exp II, Ss received either reasonable-doubt or preponderance-of-evidence instructions. After providing initial verdict preferences, some Ss deliberated in groups composed with an initial 2:2 split, whereas other Ss privately generated arguments for each verdict option. A significant asymmetry was found for groups in the reasonable-doubt condition, but group verdicts were symmetrical under the preponderance-of-evidence instructions. Shifts toward leniency in individual verdict preferences occurred for group members, but not for subjects who performed the argument-generation task. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Postidentification feedback affects subsequent eyewitness identification performance.

Eyewitnesses sometimes view more than one lineup during an investigation. We investigated the effects of postidentification feedback following one lineup on responses to a second lineup. Witnesses (N = 621) viewed a mock crime and, later, attempted to identify the culprit from an initial (target-absent) lineup and a second (target-present or target-absent) lineup. Prior to viewing the second lineup, some witnesses received accurate feedback stating that the initial lineup did not contain the culprit. A compound-decision, signal detection approach allowed the effects of feedback on identification responses to be described in terms of differences in discriminability and response bias. For witnesses who made an incorrect foil identification from the initial lineup, feedback (vs. no feedback) was associated with poorer discriminability on the second test. For witnesses who correctly rejected the initial lineup, feedback (vs. no feedback) was associated with greater discriminability on the second test. Only witnesses who received feedback after an initial correct rejection performed at a level comparable with a single-lineup control group, suggesting that an initial identification test can impair, but not enhance, performance on a second test involving the same culprit. From a theoretical perspective, the results are consistent with the idea that the way people use memorial information when making memory decisions is flexible. Analyses of preidentification confidence ratings, obtained in a follow-up study (N = 133), suggested that the effects of feedback on identification performance may have operated via differences in witnesses' metacognitive beliefs. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Human versus computerized evaluations of polygraph data in a laboratory setting.

Computer algorithms that process physiological reactions to polygraph test questions and assess the probability that the questions were answered truthfully were evaluated with data obtained in two mock crime experiments. One half of the subjects in each experiment were guilty of committing a mock theft, and one half were innocent. Data from 100 subjects in one experiment (standardization sample) were used to develop a discriminant function of electrodermal, cardiovascular, and respiration measures. The distributions of discriminant scores were used to derive Bayesian assessments of the probability of truthfulness. Data from 48 subjects in another experiment were used to cross validate the computer model (validation sample). Dichotomous computer classifications of subjects in the standardization sample were 93% correct. Blind numerical evaluations of the same data by an expert interpreter were 89% correct. On cross-validation, computer outcomes were 94% correct, and numerical evaluations were 92% correct. There were no significant differences between computer and human evaluations. The findings suggest that computer techniques may be developed for applied settings and would perform at least as well as expert human interpreters. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Reducing the biasing effects of judges' nonverbal behavior with simplified jury instruction.

This research hypothesized that using simpler jury instructions would reduce jurors' reliance on judges' nonverbal behavior. Mock jurors were given either standard or simplified jury instructions, heard actual trial testimony, and then saw a judge reading jury instructions (i.e., a judge who had an expectation or belief of either guilt or innocence for a defendant). This experiment was conducted twice, once with a student population and once with an adult population. For the students neither the judges' expectations nor the jury instructions were strongly related to the jurors' verdicts. For the adults, jurors returned more guilty verdicts overall when judges thought the defendant was guilty, and this trend was moderated by the jury instructions. The relationship between judges' expectations and jurors' verdicts was strongly positive when standard instructions were given but was weaker and in the opposite direction when simplified instructions were given. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Detection of guilty knowledge: A comment on Forman and McCauley.

Forman and McCauley (1986) administered a Guilty Knowledge Test (GKT) together with two different methods of polygraphic lie detection to the same group of subjects in an analog or mock crime experiment. Their three-item GKT performed less well than did either lie detection method, although it had by far the highest specificity (i.e., the lowest rate of false-positive errors). It is shown that this GKT performed about as would be theoretically predicted and that a longer GKT (e.g., one with only 6 items) would have shown a higher sensitivity and specificity than would either lie test. Forensic polygraphers do not use the theoretically more sound method of guilty knowledge detection, in the belief that appropriate GKT items could not be designed in the field situation. I argue that this assumption is unfounded and that what is potentially one of the most accurate and socially useful of psychological tests is being arbitrarily neglected. (PsycINFO Database Record (c) 2010 APA, all rights reserved)