Self-initiated versus instructed cheating in the physiological Concealed Information Test

No practice effect on the classification accuracy of the response time concealed information test

The Response Time Concealed Information Test can reveal that a person recognizes a relevant item (probe, e.g., a murder weapon) among other, irrelevant items (controls), based on slower responses to the probe compared to the controls. A previous study (Lukács, 2022, JARMAC) analyzed the data of 14 experiments and demonstrated that classification accuracy is increased by increased test length (i.e., increased number of trials included in the analysis). However, that study left the important question open whether prior practice (whose trials are not included in the analysis) influences the classification accuracy of subsequent testing (i.e., subsequent trials included in the analysis). Reanalyzing the same data from the 14 experiments (comprising 2223 individual tests), we show that different sections of the test (each with the same number of trials), such as the first and second half of each examined test, do not differ substantially in their classification accuracy. The main implications for real-life application are that, at least up to about 600 trials, prior practice does not affect subsequent tests' results, and the number of examined relevant items or their order of presentation may be freely chosen without compromising the method's validity.

Memory detection with concurrent behavioral, autonomic, and neuroimaging measures in a mock crime

Concealed information test (CIT) has been utilized for long to perform single measurements. The combination of multiple measures outperforms single measures because of the diverse cognitive processes they reflect and the reduction in random errors facilitated by multiple measures. To further explore the performance of the CIT with multiple measurements, 57 participants were recruited and randomly assigned into guilty and innocent groups. Subsequently, simultaneously recorded reaction time (RT), skin conductance responses (SCRs), heart rate (HR), and neuroimaging data were collected from functional near-infrared spectroscopy (fNIRS) to detect participants' concealed information in a standard CIT. The results demonstrated that all indicators including RT (area under the curve (AUC) = 0.87), SCRs (AUC = 0.79), HR (AUC = 0.78), and fNIRS (channel 8, AUC = 0.85) could differentiate guilty and innocent groups. Importantly, the use of multiple indicators achieved higher detection efficiency (AUC = 0.96) compared to the use of any single indicator. These results illustrate the effectiveness and feasibility of integrating multiple indicators for concealed information detection in CIT.

Psychophysiological indexes in the detection of deception: A systematic review

Robust evidence on deception detection highlights that humans perform at chance level, especially when a truth-default cognitive threshold is crossed by the deceiver. This systematic review examined whether identification of deceptive stimuli elicits specific physiological responses in the detectors of deception. Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, five databases were searched for human studies that evaluate physiological reactivity to deceptive stimuli, along with behavioural responses. Eleven studies (thirteen experiments) were included in a qualitative synthesis. Results show that deception detection is associated with higher activity in the prefrontal cortex and temporal lobe, with a specific involvement of the temporoparietal junction, alongside the cerebellum and cingulate cortex. Specific changes in other physiological activities (i.e., heart rate, skin temperature, motor excitability) also seem to be differently associated with the detection of deception. This review suggests that detecting deception should be considered a complex decision-making process and indicates that specific physiological activity is present across different types of deceptive stimuli. Implications are promising for further developments in security and forensic sciences.

Successful use of the forced choice test for detecting concealment of semantic memory in criminal and intelligence investigations

The current study examined the validity of the forced choice test (FCT) in a forensic scenario when used to detect concealment of semantic memory (SM-FCT). We also compared the SM-FCT validity to the FCT validity in the more commonly investigated episodic memory scenario (EM-FCT). In simulating a scenario of investigating suspected members of a terror organization, 277 students were asked to deceptively deny being enrolled in a college in which they do actually study. Results indicated that the SM-FCT's validity level was within the range of the EM-FCTs' validity levels. Theoretically, the results support a cognitive-based explanation for the FCT operation mechanism. Practically, they imply that FCT can be used in criminal or intelligence investigations of suspected members of terrorist or criminal organizations or suspected perpetrators of illegal acts or acts of terrorism, in which the incriminating evidence being sought is in the realm of designated semantic memory or knowledge.

Detecting concealed information using functional near-infrared spectroscopy (fNIRS) combined with skin conductance, heart rate, and behavioral measures

In this study, brain imaging data from functional near-infrared spectroscopy (fNIRS) associated with skin conductance response (SCR), heart rate (HR), and reaction time (RT) were combined to determine if the combination of these indicators could improve the efficiency of deception detection in concealed information test (CIT). During the CIT, participants were presented with a series of names and cities that served as target, probe, or irrelevant stimuli. In the guilty group, the probe stimuli were the participants' own names and hometown cities, and they were asked to deny this information. Our results revealed that probe items were associated with longer RT, larger SCR, slower HR, and higher oxyhemoglobin (HbO) concentration changes in the inferior prefrontal gyrus (IFG), middle frontal gyrus (MFG), and the superior frontal gyrus (SFG) compared with irrelevant items for participants in the guilty group but not in the innocent group. Furthermore, our results suggested that the combination of RT, SCR, HR, and fNIRS indicators could improve the deception detection efficiency to a very high area under the ROC curve (0.94) compared with any of the single indicators (0.74-0.89). The improved deception detection efficiency might be attributed to the reduction of random error and the diversiform underlying the psychophysiological mechanisms reflected by each indicator. These findings demonstrate a feasible way to improve the deception detection efficiency by using combined multiple indicators.

Assessing Deception in Questionnaire Surveys With Eye-Tracking

Deceit often occurs in questionnaire surveys, which leads to the misreporting of data and poor reliability. The purpose of this study is to explore whether eye-tracking could contribute to the detection of deception in questionnaire surveys, and whether the eye behaviors that appeared in instructed lying still exist in spontaneous lying. Two studies were conducted to explore eye movement behaviors in instructed and spontaneous lying conditions. The results showed that pupil size and fixation behaviors are both reliable indicators to detect lies in questionnaire surveys. Blink and saccade behaviors do not seem to predict deception. Deception resulted in increased pupil size, fixation count and duration. Meanwhile, respondents focused on different areas of the questionnaire when lying versus telling the truth. Furthermore, in the actual deception situation, the linear support vector machine (SVM) deception classifier achieved an accuracy of 74.09%. In sum, this study indicates the eye-tracking signatures of lying are not restricted to instructed deception, demonstrates the potential of using eye-tracking to detect deception in questionnaire surveys, and contributes to the questionnaire surveys of sensitive issues.

Countering information leakage in the Concealed Information Test: The effects of item detailedness

Concealed Information Tests (CIT) are administered to verify whether suspects recognize certain features from a crime. Whenever it is presumed that innocent suspects were contaminated with critical information (e.g., the perpetrator had a knife), the examiner may ask more detailed questions (e.g., specific types of knives) to prevent false positives. However, this may increase the number of false negatives if the true perpetrator fails to discern specific details from its plausible irrelevant controls, or because detailed crime‐scene information may be forgotten. We examined whether presenting items at the exemplar level protects against contamination, and whether it compromises the sensitivity in a physiological CIT. Participants (N = 142) planned a mock‐robbery, with critical items encoded either at the category or at the exemplar level. The CIT was administered immediately or after a 1‐week‐delay, with questions phrased at the categorical or exemplar level. There were no effects of time delay. Results revealed that when item detailedness was congruent at encoding and testing, the SCR, HR, and RLL showed larger differential responses, as compared with incongruent conditions. Participants contaminated with crime knowledge at the categorical level did not show a CIT‐effect for crime details at the exemplar level, suggesting detailed questions may counter the leakage problem. Asking questions at the exemplar level did not reduce the CIT detection efficiency as compared to asking questions at the categorical level. The importance of congruency between encoding and testing provides examiners with a challenge, as it is difficult to estimate how details are naturally encoded.

The Concealed Information Test (CIT) depends on the assumption that only guilty suspects have crime knowledge. As this assumption cannot always be met in real‐life, examiners may probe for more detailed information. We investigated whether use of detailed items affects accuracy in the CIT, and whether this depends on congruency between crime encoding and CIT testing. The current findings speak for the use of detailed questions.

Is the CIT susceptible to misleading information? A constructive replication

The Concealed Information Test (CIT) utilizes psychophysiological measures to detect crime-related knowledge in a suspect's memory. In other words, it can discriminate between knowledgeable (guilty) and unknowledgeable (innocent) suspects. The majority of CIT research is however conducted in controlled laboratory settings, which are more resistant to external influences than realistic forensic settings. Such influences include retroactive memory interferences which may threaten the validity of the CIT. One notable example is the misinformation effect - retroactive memory distortions caused by exposure to misleading information regarding a past event. The current study is a constructive replication of Volz et al. (J Forensic Sci 2017;63:1419) examining the effects of misleading information on the CIT. Participants underwent a three-stage experiment including a mock crime, exposure to misleading information, and a CIT. Results show that when misleading information was presented, explicit memory of the mock crime was reduced, but the physiological responses to the critical CIT items were only partially attenuated. This could suggest that the detection of crime-relevant information, using skin conductance and respiration measures, might be possible even when suspects are exposed to misleading information.

Dispersion matters: Diagnostics and control data computer simulation in Concealed Information Test studies

Binary classification has numerous applications. For one, lie detection methods typically aim to classify each tested person either as "liar" or as "truthteller" based on the given test results. To infer practical implications, as well as to compare different methods, it is essential to assess the diagnostic efficiency, such as demonstrating the number of correctly classified persons. However, this is not always straightforward. In Concealed Information Tests (CITs), the key predictor value (probe-irrelevant difference) for "truthtellers" is always similar (zero on average), and "liars" are always distinguished by a larger value (i.e., a larger number resulting from the CIT test, as compared to the zero baseline). Thereby, in general, the larger predictor values a given CIT method obtains for "liars" on average, the better this method is assumed to be. This has indeed been assumed in countless studies, and therefore, when comparing the classification efficiencies of two different designs, the mean difference of "liar" predictor values in the two designs were simply compared to each other (hence not collecting "truthteller" data to spare resources). We show, based on the meta-data of 12 different experimental designs collected in response time-based CIT studies, that differences in dispersion (i.e., variance in the data, e.g. the extent of random deviations from the zero average in case of "truthtellers") can substantially influence classification efficiency-to the point that, in extreme cases, one design may even be superior in classification despite having a larger mean "liar" predictor value. However, we also introduce a computer simulation procedure to estimate classification efficiency in the absence of "truthteller" data, and validate this procedure via a meta-analysis comparing outcomes based on empirical data versus simulated data.

Distinguishing true from false confessions using physiological patterns of concealed information recognition - A proof of concept study

Wrongful conviction cases indicate that not all confessors are guilty. However, there is currently no validated method to assess the veracity of confessions. In this preregistered study, we evaluate whether a new application of the Concealed Information Test (CIT) is a potentially valid method to make a distinction between true and false admissions of guilt. Eighty-three participants completed problem-solving tasks, individually and in pairs. Unbeknownst to the participants, their team-member was a confederate, tempting the participant to break the experimental rules by assisting during an individual assignment. Irrespective of actual rule-breaking behavior, all participants were accused of cheating and interrogated. True confessors but not false confessors showed recognition of answers obtained by cheating in the individual task, as evidenced by larger physiological responses to the correct than to plausible but incorrect answers. These findings encourage further investigation on the use of memory detection to discriminate true from false confessions.

Applying the verifiability approach to deception detection in alibi witness situations

The application of alibi witness scenarios to deception detection has been overlooked. Experiment 1 was a study of the verifiability approach in which truth-telling pairs completed a mission together, whereas in lying pairs one individual completed this mission alone and the other individual committed a mock theft. All pairs were instructed to convince the interviewer that they completed the mission together by writing individual statements on their own followed by a collective statement together as a pair. In the individual statements, truth-telling pairs provided more checkable details that demonstrated they completed the mission together than lying pairs, whereas lying pairs provided more uncheckable details than truth-telling pairs. The collective statements made truth-telling pairs provide significantly more checkable details that demonstrated they were together in comparison to the individual statements, whereas no effect was obtained for lying pairs. Receiver Operating Characteristic curves revealed high accuracy rates for discriminating between truths and lies using the verifiability approach across all statement types. Experiment 2 was a lie detection study whereby observers' abilities to discriminate between truths and lies using the verifiability approach were examined. This revealed that applying the verifiability approach to collective statements improved observers' ability to accurately detect deceit. We suggest that the verifiability approach could be used as a lie detection technique and that law enforcement policies should consider implementing collective interviewing.