Event-related potentials increase the discrimination performance of the autonomic-based concealed information test

Area measure of skin conductance in the Concealed Information Test

Skin conductance (SC) is one of the indices commonly used in the autonomic Concealed Information Test (CIT), but SC amplitude is sometimes difficult to quantify. This study investigated the applicability of SC area to the CIT as an unambiguous measure of SC. Secondary analyses of an existing dataset indicated that SC area could be used to classify examinees according to their knowledge status, although the equivalence of its performance with the SC amplitude was inconclusive. Classification performance was best when the SC signal was converted to the difference from question onset and summed over 10 s after question onset. SC area produced relatively consistent evaluations of differential responses based on the amplitude for inter-item comparisons. In addition, the classification performance of SC area exceeded the chance level even for participants who showed few measurable amplitudes (low-responsive participants). A possible implication is that a tonic increase in SC occurred in response to the relevant question even in low-responsive participants, who are traditionally excluded from analysis. The use of SC area might contribute to more impartial data evaluation and broader application of the CIT. These results indicate that SC area can be used as an alternative measure of SC in the CIT.

False memories in forensic psychology: do cognition and brain activity tell the same story?

One of the most important problems in forensic psychology is the impossibility of reliably discriminating between true and false memories when the only prosecution evidence comes from the memory of a witness or a victim. Unfortunately, both children and adults can be persuaded that they have been victims of past criminal acts, usually of a sexual nature. In adults, suggestion often occurs in the context of suggestive therapies based on the belief that traumatic events are repressed, while children come to believe and report events that never occurred as a result of repeated suggestive questioning. Cognitive Researchers have designed false memory paradigms (i.e., misinformation effect, Deese-Roediger-McDermott paradigm, event implantation paradigm) to first form false memories and then determine whether it is possible to reliably differentiate between false and true memories. In the present study, we review the contribution of cognitive research to the formation of false memories and the neuropsychological approaches aimed to discriminate between true and false memories. Based on these results, we analyze the applicability of the cognitive and neuropsychological evidence to the forensic setting.

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.

Retroactive memory interference reduces false positive outcomes of informed innocents in the P300-based concealed information test

In the Concealed Information Test (CIT), differential responses between crime-relevant and crime-irrelevant items are indicative of concealed knowledge of a crime, and are used to classify an individual as either "guilty" or "innocent". However, when crime-relevant items are leaked before the test, an innocent examinee can exhibit enhanced responses to the crime-relevant items, thus causing such examinee to be wrongly classified as guilty. In an attempt to solve this problem, we examined the role of retroactive memory interference (RI) in differentiating informed innocents from guilty participants, using a P300-based CIT. Participants acquired crime-related knowledge either by committing a mock crime (guilty group) or reading a paper that described a mock crime (informed innocent group). Subsequently, the participants within each condition were randomly assigned to either an RI group, where they were exposed to new crime-related details before the CIT, or a control group. We found an interaction between guilty and RI groups: in the guilty group, there was a significant difference in P300 amplitude between the probe and irrelevant items, regardless of RI manipulation, whereas in the informed innocent group, a difference in P300 amplitude between the probe and irrelevant items was significant only in the control group, but not in the RI group. This led to an improved detection rate of the informed innocents (31% for the control group vs. 77% for the RI group). These results suggest that RI manipulation could be used to reduce the false positive outcomes of informed innocents without affecting the detection rate of guilty participants.

The discrepant effect of acute stress on cognitive inhibition and response inhibition

This study aimed to investigate how acute stress impinges on individual's cognitive inhibition and response inhibition abilities. Electroencephalography was adopted when 35 healthy adult females performing the No Go Flanker task before and after the Trier Social Stress Test. Both inhibition processes evoked N2 and P3 components, but only the response inhibition evoked the late positive potential (LPP), indicating the response inhibition needed continuous cognitive effort to inhibit the prepotent response. The N2 and the P3 amplitudes were decreased, while the LPP amplitudes were increased under acute stress. These results suggested that acute stress caused the detrimental effect by occupying cognitive resources. Contrastingly, individuals actively regulated and made more efforts to counteract the detrimental effect of acute stress on response inhibition. Thus, acute stress impaired cognitive inhibition but did not affect response inhibition.

An intra-individual approach for detecting evaluation with event-related potentials

The P3-based concealed information test (CIT) is an accurate indirect measure of non-evaluative memories (e.g., knowledge of an incriminating item). Less clear and established, however, is the accuracy of indirect measures that rely on the P3-like late positive potentials (LPPs) in discriminating evaluative (e.g., pleasant or unpleasant) memories. Using an LPP-based evaluative oddball paradigm in which participants were truthful on half of the trials about their evaluation toward pictures and concealed their evaluation on the other half of trials toward pictures, we applied an intra-individual Bayesian scheme to classify whether participants' evaluations were congruent or incongruent with a preceding context. LPPs were predictably larger to evaluatively incongruent than congruent pictures, and this LPP effect was reduced during misreporting presumably because of enhanced cognitive load. Notably, across two experiments the sensitivity (80%) was respectable during truth telling, but poor during concealment (sensitivity = 35%). Taken together, these data suggest that indirect measures such as the LPP-based evaluative oddball may be useful for detecting individual evaluation, but more work is warranted that explores conditions under which concealment of evaluation may be more accurately assessed.

Hierarchical Bayesian models for the autonomic-based concealed information test

The concealed information test (CIT) is a psychophysiological memory detection technique for examining whether an examinee recognizes crime-relevant information. In current statistical analysis practice, the autonomic responses are usually transformed into Z scores within individuals to remove inter- and intra-individual variability. However, this conventional procedure leads to overestimation of the effect size, specifically the standardized mean difference of the autonomic responses between the crime-relevant information and the crime-irrelevant information. In this study, we attempted to resolve this problem by modeling inter- and intra-individual variability directly using hierarchical Bayesian modeling. Five models were constructed and applied to CIT data obtained from 167 participants. The validity of the CIT was confirmed using Bayesian estimates of the effect sizes, which are more accurate and interpretable than conventional effect sizes. Moreover, hierarchical Bayesian modeling provided information that is not available from the conventional statistical analysis procedure.

Single-trial lie detection using a combined fNIRS-polygraph system

Deception is a human behavior that many people experience in daily life. It involves complex neuronal activities in addition to several physiological changes in the body. A polygraph, which can measure some of the physiological responses from the body, has been widely employed in lie-detection. Many researchers, however, believe that lie detection can become more precise if the neuronal changes that occur in the process of deception can be isolated and measured. In this study, we combine both measures (i.e., physiological and neuronal changes) for enhanced lie-detection. Specifically, to investigate the deception-related hemodynamic response, functional near-infrared spectroscopy (fNIRS) is applied at the prefrontal cortex besides a commercially available polygraph system. A mock crime scenario with a single-trial stimulus is set up as a deception protocol. The acquired data are classified into “true” and “lie” classes based on the fNIRS-based hemoglobin-concentration changes and polygraph-based physiological signal changes. Linear discriminant analysis is utilized as a classifier. The results indicate that the combined fNIRS-polygraph system delivers much higher classification accuracy than that of a singular system. This study demonstrates a plausible solution toward single-trial lie-detection by combining fNIRS and the polygraph.

A novel algorithm to enhance P300 in single trials: application to lie detection using F-score and SVM

The investigation of lie detection methods based on P300 potentials has drawn much interest in recent years. We presented a novel algorithm to enhance signal-to-noise ratio (SNR) of P300 and applied it in lie detection to increase the classification accuracy. Thirty-four subjects were divided randomly into guilty and innocent groups, and the EEG signals on 14 electrodes were recorded. A novel spatial denoising algorithm (SDA) was proposed to reconstruct the P300 with a high SNR based on independent component analysis. The differences between the proposed method and our/other early published methods mainly lie in the extraction and feature selection method of P300. Three groups of features were extracted from the denoised waves; then, the optimal features were selected by the F-score method. Selected feature samples were finally fed into three classical classifiers to make a performance comparison. The optimal parameter values in the SDA and the classifiers were tuned using a grid-searching training procedure with cross-validation. The support vector machine (SVM) approach was adopted to combine with an F-score because this approach had the best performance. The presented model F-score_SVM reaches a significantly higher classification accuracy for P300 (specificity of 96.05%) and non-P300 (sensitivity of 96.11%) compared with the results obtained without using SDA and compared with the results obtained by other classification models. Moreover, a higher individual diagnosis rate can be obtained compared with previous methods, and the presented method requires only a small number of stimuli in the real testing application.

Reading aloud: a psychophysiological investigation in children

This study investigated the electrophysiological responses to single-letter reading in children (reading-related potentials) and explored the morphological differences between covert and overt reading conditions. Sixty-five healthy children (6-13 years) participated in this study. Reading-related potentials were recorded during visual stimulation with single Italian alphabetic letters. Stimuli were displayed for 5 ms either automatically at a randomly jittered time lag or upon voluntary self-paced button press by children. In the covert conditions, children had to passively look at single letters, while in the overt conditions children were required to read aloud the letters. Electromyographic activity of the forearm and lips was additionally recorded during all tasks. Superimposition of reading-related potentials with the electromyographic activity of forearm and lips during self-paced reading aloud allowed to segregate the reading-related components into four periods: preparatory, pre-lexical, lexical and post-lexical. Reading-related potentials of the preparatory period can be related to preparation/intention to read, those of the pre-lexical period to visual-perceptual processes, those of the lexical period to the external/internal reafferent activity and those of the post-lexical period to the feedback processes following task completion. Analysis of variance showed a significant interaction of reading-related components with electrode locations and task conditions in all periods. The systematic characterization of the neurophysiological correlates of the elementary association between letters and sounds is helpful to highlight the neurobiological and functional basis of reading in healthy as well as impaired readers, for possibly developing neurophysiologically grounded rehabilitation therapies and further improving the explanatory models of dyslexia.

The current and future status of the concealed information test for field use

The Concealed Information Test (CIT) is a psychophysiological technique for examining whether a person has knowledge of crime-relevant information. Many laboratory studies have shown that the CIT has good scientific validity. However, the CIT has seldom been used for actual criminal investigations. One successful exception is its use by the Japanese police. In Japan, the CIT has been widely used for criminal investigations, although its probative force in court is not strong. In this paper, we first review the current use of the field CIT in Japan. Then, we discuss two possible approaches to increase its probative force: sophisticated statistical judgment methods and combining new psychophysiological measures with classic autonomic measures. On the basis of these considerations, we propose several suggestions for future practice and research involving the field CIT.

P300 amplitudes in the concealed information test are less affected by depth of processing than electrodermal responses

The Concealed Information Test (CIT) has been used in the laboratory as well as in field applications to detect concealed crime related memories. The presentation of crime relevant details to guilty suspects has been shown to elicit enhanced N200 and P300 amplitudes of the event-related brain potentials (ERPs) as well as greater skin conductance responses (SCRs) as compared to neutral test items. These electrophysiological and electrodermal responses were found to incrementally contribute to the validity of the test, thereby suggesting that these response systems are sensitive to different psychological processes. In the current study, we tested whether depth of processing differentially affects N200, P300, and SCR amplitudes in the CIT. Twenty participants carried out a mock crime and became familiar with central and peripheral crime details. A CIT that was conducted 1 week later revealed that SCR amplitudes were larger for central details although central and peripheral items were remembered equally well in a subsequent explicit memory test. By contrast, P300 amplitudes elicited by crime related details were larger but did not differ significantly between question types. N200 amplitudes did not allow for detecting concealed knowledge in this study. These results indicate that depth of processing might be one factor that differentially affects central and autonomic nervous system responses to concealed information. Such differentiation might be highly relevant for field applications of the CIT.