Detecting Concealed Information Using Functional Near-Infrared Spectroscopy

Similarities and Distinctions between Cortical Neural Substrates That Underlie Generation of Malevolent Creative Ideas

Creativity can be driven by negative intentions, and this is called malevolent creativity (MC). It is a type of creativity that serves antisocial purposes and deliberately leads to harmful or immoral results. A possible classification indicates that there are three kinds of MC in daily life: hurting people, lying, and playing tricks. This study aimed to explore similar and distinct neural substrates underlying these different kinds of MC idea generation. The participants were asked to perform different MC tasks, and their neural responses were recorded using a functional near-infrared spectroscopy device. The findings revealed that most regions within the prefrontal and temporal lobes [e.g., the right dorsolateral prefrontal cortex (rDLPFC), and right angular gyrus] were involved in the three MC tasks. However, the right frontopolar cortex (rFPC) was more activated and less coupled with the rDLPFC and right precuneus during the lying task than during the other tasks. Thus, rFPC may play an important role in constructing novel lies. In the lying task, individuals were more selfish and less compassionate. In the playing tricks and hurting people tasks, there was less neural coupling between the rDLPFC and the left inferior frontal gyrus/right inferior parietal lobule than that in the lying task. This may imply that selfish motivation is released when individuals try to ignore victims' distress or generate aggressive tricks in hurting people or playing tricks tasks. These findings indicate that the three kinds of MC idea generation involve common cortical regions related to creative idea generation and moral judgment, whereas differences in cortical responses exist because of their unique features.

Neural correlates of bribe-taking decision dilemma: An fNIRS study

Bribe-taking decision is a social dilemma for individuals: the pursuit of economic self-interest vs. compliance with social norms. Despite the well-known existence of the conflict in deciding whether to accept bribes, little is known about its neural responses. Using functional near-infrared imaging (fNIRS) technology and the bribe-taking decision game (economic gambling game as a control condition), the current study dissociated the neural correlates of the different motivations in the bribery dilemma, as well as the inhibitory effect of social norms on bribery and its underlying brain mechanisms in supra-cortical regions. Findings revealed that if individuals are more motivated by economic interest, rejecting money (vs. accepting money) accompanies higher activity in the dorsolateral prefrontal cortex (DLPFC) and frontopolar cortex (FPC), which reflects impulse inhibition and decision evaluation; whereas, if individuals are more consider social norms, their DLPFC is more active when they accept bribes (vs. reject bribes), which reflects their fear of punishment. Additionally, the key brain region where social norms inhibit bribery involves the left DLPFC. The current findings contribute to the literature on the neural manifestations of corrupt decisions and provide some insights into the anti-corruption movement.

CAS(ME)3: A Third Generation Facial Spontaneous Micro-Expression Database With Depth Information and High Ecological Validity

Micro-expression (ME) is a significant non-verbal communication clue that reveals one person's genuine emotional state. The development of micro-expression analysis (MEA) has just gained attention in the last decade. However, the small sample size problem constrains the use of deep learning on MEA. Besides, ME samples distribute in six different databases, leading to database bias. Moreover, the ME database development is complicated. In this article, we introduce a large-scale spontaneous ME database: CAS(ME) 3. The contribution of this article is summarized as follows: (1) CAS(ME) 3 offers around 80 hours of videos with over 8,000,000 frames, including manually labeled 1,109 MEs and 3,490 macro-expressions. Such a large sample size allows effective MEA method validation while avoiding database bias. (2) Inspired by psychological experiments, CAS(ME) 3 provides the depth information as an additional modality unprecedentedly, contributing to multi-modal MEA. (3) For the first time, CAS(ME) 3 elicits ME with high ecological validity using the mock crime paradigm, along with physiological and voice signals, contributing to practical MEA. (4) Besides, CAS(ME) 3 provides 1,508 unlabeled videos with more than 4,000,000 frames, i.e., a data platform for unsupervised MEA methods. (5) Finally, we demonstrate the effectiveness of depth information by the proposed depth flow algorithm and RGB-D information.

Prefrontal Cerebral Oxygenated Hemoglobin Concentration during the Category Fluency and Finger-Tapping Tasks in Adults with and without Mild Cognitive Impairment: A Near-Infrared Spectroscopy Study

Mild cognitive impairment (MCI) is considered to be the limit between the cognitive changes of aging and early dementia; thus, discriminating between participants with and without MCI is important. In the present study, we aimed to examine the differences in the cerebral oxyhemoglobin signal between individuals with and without MCI. The cerebral oxyhemoglobin signal was measured when the participants (young and elderly controls as well as patients with MCI) performed category fluency, finger tapping, and dual tasks using head-mounted near-infrared spectroscopy; the results were compared between the groups. The cerebral oxyhemoglobin signal trended toward the highest values during the category fluency task in young participants and during the finger-tapping task in elderly participants regardless of the MCI status. The area under the curve was approximately 0.5, indicating a low discrimination ability between elderly participants with and without MCI. The measurement of the blood flow in the prefrontal cortex may not accurately quantify cognitive and motor performance to detect MCI. Finger tapping may increase cerebral blood flow in individuals with and without MCI during the task.

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.

Middle Occipital Area Differentially Associates with Malevolent versus Benevolent Creativity: An fNIRS investigation

This study aimed to explore the neural correlates underlying idea generation during malevolent creativity (MC) using functional near-infrared spectroscopy (fNIRS). Participants were asked to solve problems during three types of creativity tasks: malevolent creativity task (MCT), benevolent creativity task (BCT), and alternative uses task (AUT). fNIRS was used to record individual cerebral activity during the tasks. The results revealed that participants demonstrated weaker neural activation in the right middle occipital area (rMO) and lower neural coupling (NC) between the right frontopolar cortex (rFPC) and rMO during MCT than during BCT and AUT. These suggest that r-MO activity and NC between the rFPC and rMO may distinguish between malevolent and benevolent forms of creative ideation.

Cooperation with partners of differing social experience: An fNIRS-based hyperscanning study

Previous studies have shown the brain synchronization of all team members while completing a collaborative task. Moreover, this effect is influenced by a team's compositional elements, such as gender (opposite or same) or relationships (i.e., friends, lovers, or strangers) among team members. However, whether interpersonal brain synchronization (IBS) is affected by team members' experience, as well as the temporal dynamics of such brain synchronization, remains to be investigated. In the current study, we combined behavioral methods and functional near-infrared spectroscopy-based hyperscanning to examine the effect of member experience on team cooperation by an adopted continuous joint drawing task with 21 student-student dyads (S-S dyads) and 22 teacher-student dyads (T-S dyads). The results revealed that team members with differing experiences (T-S dyads) perform better than those with similar ones (S-S dyads). Moreover, we observed IBS in the left frontopolar region (channel 11). However, we did not observe significant changes of the task-related IBS across time. Besides, IBS was negatively correlated with the participants' behavioral performance. Our findings demonstrate the importance of social experience in teamwork in the real world and suggest a possible mechanism for cooperation from a temporal and spatial perspective.

Educational diversity and group creativity: Evidence from fNIRS hyperscanning

Educational diversity is defined as the diversity of educational backgrounds measured by multiple subjects. This study aimed to unveil the interpersonal neural correlates that underlie the effect of group educational diversity on group creativity. One hundred and sixteen college students were assigned to high educational diversity (HD; the members respectively majored in science or social science) or low educational diversity (LD; the members both majored in either science or social science) groups based on their academic majors. They were required to solve two problems that either demanded creativity (alternative uses task, AUT) or not (object characteristics task). We used functional near-infrared spectroscopy (fNIRS)-based hyperscanning to simultaneously record the neural responses of pairs of interacting participants in each group. The LD group showed more AUT fluency and perspective-taking behaviours than the HD group, whereas no group difference was observed for AUT uniqueness. Additionally, collective flexibility was higher in the HD group than in the LD group. The fNIRS results showed that the interpersonal brain synchronisation (IBS) increments at the right angular gyrus and right primary somatosensory cortex were greater in the LD group than in the HD group. These findings indicate that although high educational diversity benefits cognitive flexibility, it does not necessarily lead to a better idea quality or greater idea quantity. The greater IBS increments and perspective-taking behaviours that we observed in the LD group may account for this.

Neural correlates of spontaneous deception in a non-competitive interpersonal scenario: A functional near-infrared spectroscopy (fNIRS) study

This study aims to examine neural correlates of spontaneous deception in a non-competitive interpersonal situation, and the difference in neural correlates between spontaneous deception and instructed deception using functional near-infrared spectroscopy (fNIRS). We used a modified poker game in which participants freely decided whether sending a piece of truthful/deceptive information to other participants. In the instructed session, participants sent truthful/deceptive information per the instructions. In this non-competitive interpersonal situation in the orbitofrontal cortex (OFC) and dorsolateral prefrontal cortex (DLPFC), deception produced higher neural activities than truth-telling. In addition, spontaneous deception exhibited higher neural activities than instructed deception in the frontopolar area, DLPFC, and frontal eye fields. Spontaneous truth-telling produced higher neural activities than instructed truth-telling in frontal eye fields and frontopolar area. This study provides evidence about neural correlates of spontaneous deception during non-competitive interpersonal scenarios and the difference between spontaneous deception and instructed deception.

A Look Into the Power of fNIRS Signals by Using the Welch Power Spectral Estimate for Deception Detection

Neuroimaging technologies have improved our understanding of deception and also exhibit their potential in revealing the origins of its neural mechanism. In this study, a quantitative power analysis method that uses the Welch power spectrum estimation of functional near-infrared spectroscopy (fNIRS) signals was proposed to examine the brain activation difference between the spontaneous deceptive behavior and controlled behavior. The power value produced by the model was applied to quantify the activity energy of brain regions, which can serve as a neuromarker for deception detection. Interestingly, the power analysis results generated from the Welch spectrum estimation method demonstrated that the spontaneous deceptive behavior elicited significantly higher power than that from the controlled behavior in the prefrontal cortex. Meanwhile, the power findings also showed significant difference between the spontaneous deceptive behavior and controlled behavior, indicating that the reward system was only involved in the deception. The proposed power analysis method for processing fNIRS data provides us an additional insight to understand the cognitive mechanism of deception.

The Role of Reward System in Dishonest Behavior: A Functional Near-Infrared Spectroscopy Study

Previous studies showed that the cortical reward system plays an important role in deceptive behavior. However, how the reward system activates during the whole course of dishonest behavior and how it affects dishonest decisions remain unclear. The current study investigated these questions. One hundred and two participants were included in the final analysis. They completed two tasks: monetary incentive delay (MID) task and an honesty task. The MID task served as the localizer task and the honesty task was used to measure participants' deceptive behaviors. Participants' spontaneous responses in the honesty task were categorized into three conditions: Correct-Truth condition (tell the truth after guessing correctly), Incorrect-Truth condition (tell the truth after guessing incorrectly), and Incorrect-Lie condition (tell lies after guessing incorrectly). To reduce contamination from neighboring functional regions as well as to increase sensitivity to small effects (Powell et al., Devel Sci 21:e12595, 2018), we adopted the individual functional channel of interest (fCOI) approach to analyze the data. Specially, we identified the channels of interest in the MID task in individual participants and then applied them to the honesty task. The result suggested that the reward system showed different activation patterns during different phases: In the pre-decision phase, the reward system was activated with the winning of the reward. During the decision and feedback phase, the reward system was activated when people made the decisions to be dishonest and when they evaluated the outcome of their decisions. Furthermore, the result showed that neural activity of the reward system toward the outcome of their decision was related to subsequent dishonest behaviors. Thus, the present study confirmed the important role of the reward system in deception. These results can also shed light on how one could use neuroimaging techniques to perform lie-detection.

Cooperation Makes a Group be More Creative

This study investigated how cooperative and competitive interaction modes affect the group creative performance. The participants were recruited as dyads to solve 2 problems either demanding divergent thinking (alternative uses task, AUT) or not (object characteristic task, OCT). The dyads solved 1 of the 2 problems in the cooperative mode and the other in the competitive mode. Functional near-infrared spectroscopy (fNIRS)-based hyperscanning was used to record their neural activities in the prefrontal and right temporal-parietal junction (r-TPJ) regions. Results revealed the dyads showed higher AUT fluency, AUT originality, OCT fluency, and cooperation level in the cooperative mode than in the competitive mode. The fNIRS data revealed increased (task-baseline) interpersonal brain synchronization (IBS) in the right dorsolateral prefrontal cortex (r-DLPFC) and r-TPJ, only for dyads in the AUT/cooperation condition. In both r-DLPFC and r-TPJ, the IBS of dyads in the AUT/cooperation condition was stronger than in the AUT/competition and OCT/cooperation. Moreover, a stronger IBS was evoked between the regions in prefrontal and posterior temporal regions in the AUT/cooperation condition, as compared with the competition mode. These findings suggest that enhanced IBS may underlie the positive effects of cooperation as compared with the competition in terms of group creativity.

Gender of partner affects the interaction pattern during group creative idea generation

This study aimed to determine how gender composition affects the group creative process. Participants were recruited into dyads with different gender compositions (female-male dyad, F-M; female-female, F-F; male-male, and M-M) to solve two problems. One problem demanded creativity alternative use task (AUT) and the other did not object characteristic task. Functional near-infrared spectroscopy (fNIRS)-based hyperscanning was used to record interpersonal neural responses. Results demonstrated no significant difference in creative performance among the three types of dyads. However, the F-F dyad showed higher levels of cooperative behaviour (i.e. the index of convergence) and collective flexibility than the other dyads. Also, in the fNIRS data, the F-F dyad showed higher interpersonal brain synchronization (IBS) increments in the right posterior parietal cortex during the AUT than the other dyads, which covaried with their creative performance. These findings indicate that while solving a creativity problem together, females are more likely than males to consider others' perspectives. This gender difference might be due to the enhanced IBS increment in the right posterior parietal cortex.

When do we fall in neural synchrony with others?

This study aimed to investigate the situation in which interpersonal brain synchronization (IBS) occurs during a collaborative task and examined its trajectory over time by developing a novel functional near-infrared spectroscopy (fNIRS)-based hyperscanning paradigm. Participants were asked to perform a collaborative task in three-person groups where two of the members are real participants and one is a confederate. Compared to dyads between real participants and confederates, real-participant pairings showed greater cooperation behavior and IBS between bilateral dorsolateral prefrontal cortex. And, IBS and cooperation increased over time in real-participant pairings, whereas they remained low and constant in dyads with the confederate. These findings indicate that IBS occurs between individuals engaging in interpersonal interaction during a collaborative task, during which both IBS and cooperatively interpersonal interaction tend to increase over time.

Behavioral and brain synchronization differences between expert and novice teachers when collaborating with students

Differences in behavior and neural mechanisms between expert and novice teachers when collaborating with students are poorly understood. This study investigated whether expert teachers do better in collaborating with students than novice teachers and explored the neural basis of such differences. Novice teacher and student (NT-S) dyads and expert teacher and student (ET-S) dyads were recruited to complete an interactive task consisting of a cooperation and an independent condition. During the experiment, neural activity in the prefrontal cortex of the participants was recorded with functional near-infrared spectroscopy. The results show higher accuracy for the ET-S dyads than the NT-S dyads in the cooperation condition; however, no difference was found in the independent condition. Increased interpersonal brain synchronization (IBS) was detected in the left dorsolateral prefrontal cortex of participants in ET-S dyads, but not in NT-S dyads in the cooperation condition. Moreover, an interaction effect of dyad type and conditions on IBS was observed, revealing IBS was stronger in ET-S dyads than in NT-S dyads. In ET-S dyads, IBS was positively correlated with the teachers' perspective-taking ability and accuracy. These findings suggest that expert teachers collaborate better with students than novice teachers, and IBS might be the neural marker for this difference.

Neuroethics of Non-primary Brain Computer Interface: Focus on Potential Military Applications

The field of neuroethics has had to adapt rapidly in the face of accelerating technological advancement; a particularly striking example is the realm of Brain-Computer Interface (BCI). A significant source of funding for the development of new BCI technologies has been the United States Department of Defense, and while the predominant focus has been restoration of lost function for those wounded in battle, there is also significant interest in augmentation of function to increase survivability, coordination, and lethality of US combat forces. While restoration of primary motor and sensory function (primary BCI) has been the main focus of research, there has been marked progress in interface with areas of the brain subserving memory and association. Non-Primary BCI has a different subset of potential applications, each of which also carries its own ethical considerations. Given the amount of BCI research funding coming from the Department of Defense, it is particularly important that potential military applications be examined from a neuroethical standpoint.

Detecting Concealed Information with Fused Electroencephalography and Functional Near-infrared Spectroscopy

In this study, fused electroencephalography (EEG) and functional near-infrared spectroscopy (fNIRS) techniques were utilized to examine the relationship between the ERP (event-related potential) component P300 and fNIRS hemodynamic signals for high-accuracy deception detection. During the performance of a modified concealed information test (CIT) task, a series of Chinese names were presented, which served as the target, irrelevant, or the probe stimuli for both the guilty and innocent groups. For participants in the guilty group, the probe stimulus was their individual name, whereas for the innocent group, the probe stimulus was one irrelevant name. In particular, data from concurrent fNIRS and ERP recordings were carefully inspected for participants from the two groups. Interestingly, we discovered that for the guilty group, the probe stimulus elicited significantly higher P300 amplitude at parietal site and also evoked significantly stronger oxyhemoglobin (HbO) concentration changes in the bilateral superior frontal gyrus and bilateral middle frontal gyrus than the irrelevant stimuli. However, this is not the case for the innocent group, in which participants exhibited no significant differences in both ERP and fNIRS measures between the probe and irrelevant stimuli. More importantly, our findings also demonstrated that the combined ERP and fNIRS feature was able to differentiate the guilty and innocent groups with enhanced sensitivity, in which AUC (the area under Receiver Operating Characteristic curve) is 0.94 for deception detection based on the combined indicator, much higher than that based on the ERP component P300 only (0.85) or HbO measure only (0.84).

Lie Detection Using fNIRS Monitoring of Inhibition-Related Brain Regions Discriminates Infrequent but not Frequent Liars

Functional near-infrared spectroscopy (fNIRS) was used to test whether monitoring inhibition-related brain regions is a feasible method for detecting both infrequent liars and frequent liars. Thirty-two participants were divided into two groups: the deceptive group (liars) and the non-deceptive group (ND group, innocents). All the participants were required to undergo a simulated interrogation by a computer. The participants from the deceptive group were instructed to tell a mix of lies and truths and those of the ND group were instructed always to tell the truth. Based on the number of deceptions, the participants of the deceptive group were further divided into a infrequently deceptive group (IFD group, infrequent liars) and a frequently deceptive group (FD group, frequent liars). The infrequent liars exhibited greater neural activities than the frequent liars and the innocents in the left middle frontal gyrus (MFG) when performing the deception detection tasks. While performing deception detection tasks, infrequent liars showed significantly greater neural activation in the left MFG than the baseline, but frequent liars and innocents did not exhibit this pattern of neural activation in any area of inhibition-related brain regions. The results of individual analysis showed an acceptable accuracy of detecting infrequent liars, but an unacceptable accuracy of detecting frequent liars. These results suggest that using fNIRS monitoring of inhibition-related brain regions is feasible for detecting infrequent liars, for whom deception may be more effortful and therefore more physiologically marked, but not frequent liars.

Feasibility of Functional Near-Infrared Spectroscopy (fNIRS) to Investigate the Mirror Neuron System: An Experimental Study in a Real-Life Situation

The mirror neuron system (MNS), mainly including the premotor cortex (PMC), inferior frontal gyrus (IFG), superior parietal lobule (SPL), and rostral inferior parietal lobule (IPL), has attracted extensive attention as a possible neural mechanism of social interaction. Owing to high ecological validity, functional near-infrared spectroscopy (fNIRS) has become an ideal approach for exploring the MNS. Unfortunately, for the feasibility of fNIRS to detect the MNS, none of the four dominant regions were found in previous studies, implying a very limited capacity of fNIRS to investigate the MNS. Here, we adopted an experimental paradigm in a real-life situation to evaluate whether the MNS activity, including four dominant regions, can be detected by using fNIRS. Specifically, 30 right-handed subjects were asked to complete a table-setting task that included action execution and action observation. A double density probe configuration covered the four regions of the MNS in the left hemisphere. We used a traditional channel-based group analysis and also a ROI-based group analysis to find which regions are activated during both action execution and action observation. The results showed that the IFG, adjacent PMC, SPL, and IPL were involved in both conditions, indicating the feasibility of fNIRS to detect the MNS. Our findings provide a foundation for future research to explore the functional role of the MNS in social interaction and various disorders using fNIRS.

Human cortical neural correlates of visual fatigue during binocular depth perception: An fNIRS study

Functional near-infrared spectroscopy (fNIRS) was adopted to investigate the cortical neural correlates of visual fatigue during binocular depth perception for different disparities (from 0.1° to 1.5°). By using a slow event-related paradigm, the oxyhaemoglobin (HbO) responses to fused binocular stimuli presented by the random-dot stereogram (RDS) were recorded over the whole visual dorsal area. To extract from an HbO curve the characteristics that are correlated with subjective experiences of stereopsis and visual fatigue, we proposed a novel method to fit the time-course HbO curve with various response functions which could reflect various processes of binocular depth perception. Our results indicate that the parietal-occipital cortices are spatially correlated with binocular depth perception and that the process of depth perception includes two steps, associated with generating and sustaining stereovision. Visual fatigue is caused mainly by generating stereovision, while the amplitude of the haemodynamic response corresponding to sustaining stereovision is correlated with stereopsis. Combining statistical parameter analysis and the fitted time-course analysis, fNIRS could be a promising method to study visual fatigue and possibly other multi-process neural bases.

New frontiers in time-domain diffuse optics, a review

The recent developments in time-domain diffuse optics that rely on physical concepts (e.g., time-gating and null distance) and advanced photonic components (e.g., vertical cavity source-emitting laser as light sources, single photon avalanche diode, and silicon photomultipliers as detectors, fast-gating circuits, and time-to-digital converters for acquisition) are focused. This study shows how these tools could lead on one hand to compact and wearable time-domain devices for point-of-care diagnostics down to the consumer level and on the other hand to powerful systems with exceptional depth penetration and sensitivity.

Mapping the small-world properties of brain networks in deception with functional near-infrared spectroscopy

Deception is not a rare occurrence among human behaviors; however, the present brain mapping techniques are insufficient to reveal the neural mechanism of deception under spontaneous or controlled conditions. Interestingly, functional near-infrared spectroscopy (fNIRS) has emerged as a highly promising neuroimaging technique that enables continuous and noninvasive monitoring of changes in blood oxygenation and blood volume in the human brain. In this study, fNIRS was used in combination with complex network theory to extract the attribute features of the functional brain networks underling deception in subjects exhibiting spontaneous or controlled behaviors. Our findings revealed that the small-world networks of the subjects engaged in spontaneous behaviors exhibited greater clustering coefficients, shorter average path lengths, greater average node degrees, and stronger randomness compared with those of subjects engaged in control behaviors. Consequently, we suggest that small-world network topology is capable of distinguishing well between spontaneous and controlled deceptions.

Using functional near-infrared spectroscopy (fNIRS) to detect the prefrontal cortical responses to deception under different motivations

In this study, functional near-infrared spectroscopy (fNIRS) was adopted to investigate the prefrontal cortical responses to deception under different motivations. By using a feigned memory impairment paradigm, 19 healthy adults were asked to deceive under the two different motivations: to obtain rewards and to avoid punishments. Results indicated that when deceiving for obtaining rewards, there was greater neural activation in the right inferior frontal gyrus (IFG) than the control condition. When deceiving for avoiding punishments, there was greater activation in the right inferior frontal gyrus (IFG) and the left middle frontal gyrus (MFG) than the control condition. In addition, deceiving for avoiding punishments led to greater neural activation in the left MFG than when deceiving for obtaining rewards. Furthermore, the results showed a moderate hit rate in detecting deception under either motivation. These results demonstrated that deception with different motivations led to distinct responses in the prefrontal cortex. fNIRS could provide a useful technique for the detection of deception with strategy of feigning memory impairment under different motivations.

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.