The broadest definition portrays deception as social behavior in which one individual deliberately attempts to persuade or convince another to accept as true what the deceiver believes to be false. Self-presentation is one of the reasons for lying and people have lied about their emotions and feelings, actions, accomplishments and knowledge (DePaulo, Kashy, & Kirkendol, 1996).
A false remark which is told with the intention of deceiving is called a Lie (Chambers, 1991).
A lot of nonverbal cues have been found by the researchers which are associated with deception, but most of them are evidently not reliable. For example, microexpressions, such as head shaking or negative facial expressions (Mehrabian, 1971) (Burgoon & Buller, 1994), the pitch of the voice tends to be raise when people are engaged in deception (Vrij A. , 1994), their body posture generally becomes more rigid when one lies (Mehrabian, 1971) (Vrij A. , 1994)and alterations in patterns of eye contact can be seen (Horvath, Jayne, & Buckley, 1994). These behavioral cues reflect increased physiological arousal during deception, which may arise because the individual feels guilty, is afraid of being detected, or is excited at the thought of deceiving others (Ekman, 1992). Researchers and criminologists devised Polygraph- a machine based technique that attempts to detect arousal, monitor physiological functions such as heart rate, breathing rate, and skin conductance in order to detect Deception (Scientific validity of polygraph testing: a research review and evaluation — a technical memorandum., 1983).
A growing no. of researchers have used FMRI(Functional Magnetic Resonance Imaging) and PET(Positron Emission Tomography) to clarify the neural correlates of deception. Spence was one of the first ones to report a FMRI study of deception. They found that longer reaction times and increased activity in the ventrolateral prefrontal cortex is related to lying (Spence, Farrow, & Herford, Behavioural and functional anatomical correlates of deception in humans, 2001). These neuroimaging techniques are used to detect deception as well as to differentiate the neurocognitive processes underlying deception (Furedy, Davis, & Gurevich, 1988).
A lot of researches have been conducted that revealed the biological basis of deception. Langleben used guilty knowledge test(GKT) along with fMRI and an increase in the activity in superior frontal gyrus and anterior cingulate cortex was seen which is related to deception. (Lee , Liu, & Tan, 2002). Ganis dissociated the neural correlates of different sorts of deception. They stated that the anterior prefrontal cortex was involved in general deception but the right anterior prefrontal activity was more engaged in well rehersed lies rather than spontaneous lies. (Ganis, Kosslyn, & Stose, 2003). Kozel and his studies focused on knowledge gained through past personal action. Specifically, participants were prompted to lie about the location of money (i.e., a $50 bill) which they had learned through recent personal experience (i.e., participants were instructed to search under various items in a room to locate the money) which found that the orbitofrontal cortex and anterior cingulate cortex were singnificanty activated during deception. (Kozel, Revell, & Lorberbaum, 2004)
An investigation was also done to know whether men and women contrast when falsifying general (self-irrelevant) and personal (self-relevant) information. The result suggested that it was more difficult for the men to lie about personal information than general information, whereas for women both types of lying had similar levels of difficulty. Differences were also found in neural correlates underlying deceptive responses between men and women. (Marchewka, Jednorog, Falkiewicz, Szeszkowski, Grabowska, & Szatkowska, 2012).
Abe and Lee reported that increased prefrontal activity was found during deception as it reflected neural correlation of intentional falsification of responses, whereas such activity was not observed with unintentional memory errors (Lee, Au, & Liu, 2009). H215O PET experiment was led by Abe with a novel twist, in which participants were instructed to deceive the other experimenter. PET was appropriate in the light of the fact that it allowed direct communication between individuals and experimenters. Activation of the ventromedial prefrontal cortex and the amygdala(involved in deception), both of which are key regions for social interactions, was seen during the experiment (Abe, Suzuki, & Mori, Deceiving others: distinct neural responses of the prefrontal cortex and amygdala in simple fabrication and deception with social interactions., 2007). However, according to Sip it was unrealistic because there was a narrow choice for the wrongdoing and absence of unpleasant consequences if deception was discovered (Sip , Roepstorff, McGregor, & Frith, 2008).
Greene and Paxton conducted a fMRI experiment combined with novel deception tasks in which individuals could gain monetary reward by precisely anticipating the outcomes of computerized coin ﬂips. In some trials individuals recorded their predictions in advance, and in other trials individuals were rewarded based on self-reported accuracy, therefore, they could gain money deceitfully by lying about the accuracy of their predictions. Results revealed that dishonest individuals displayed an increase in prefrontal activity, both when choosing to behave dishonestly and during trials when they refrained from dishonesty and honest individuals did not exhibit such control-related activity when choosing to behave honestly, as compared with a control condition without any opportunity for dishonest gain. Based on these results, Greene and Paxton argued that honest behaviors are more closely linked to the absence of temptation than to the active resistance of temptation (Green & Paxton, 2009).
A 18F-ﬂuorodeoxyglucose PET by Abe interestingly revealed that Parkinson Disease’s patients face difficulties in telling lies because of decreased metabolic rates of the left dorsolateral and right anterior prefrontal regions in the brain (Abe, Fujii, & Hirayama , Do parkinsonian patients have trouble telling lies? The neurological basis of deceptive behaviour., 2009) and it is consistent with the results of another study by Abe with healthy individuals which discovered that left dorsolateral prefrontal cortex, has a role in inhibiting true responses and making deceptive responses (Abe, Suzuki, & Tsukiura, Dissociable roles of prefrontal and anterior cingulate cortices in deception., 2006).
Kikuchi showed that the right dorsolateral prefrontal cortex is related with unconscious memory repression (amnesic states), and the left dorsolateral prefrontal cortex with intentional deception (feigning ignorance) (Kikuchi, Fuji, & Abe, 2009) and further evidence from Priori and Karim’s study of transcranial direct current stimulation (noninvasive technique that elicits functional changes in the human brain without requiring direct access to the neural tissue) displayed that focal changes in the excitability of the dorsolateral prefrontal cortex after anodal transcranial direct current stimulation can alter the speed and efﬁciency of deceptive responses leading to ‘anodal block’ and impairment in prefrontal function (Priori, Mameli, & Cogiamanian, 2008) but on the contrary Karim reported that focal changes in the excitability of anterior prefrontal cortex due to cathodal TDCS facilitated the deceptive response as faster reaction times, a decrease in the sympathetic skin conductance response, a decrease in feelings of guilt, and an increased behavioral pattern of skillful lying was seen (Karim, Schnieder, & Lotze, 2009).
A set of higher order cognitive processes that allow ﬂexible modiﬁcation of thought and behavior in response to changing cognitive or environmental contexts is called Executive Control (Spence & Langleben, Detection of deception with fMRI, 2008) It has 3 components – working memory, task switching, and inhibitory control and these contribute to deception to the extent that deception involves: keeping the truth in mind while formulating a deceptive response (working memory), suppressing a truthful response (inhibitory control), and switching between truthful and deceptive responses (task switching) (Miyake, Friedman, Witzki, & Howerter, 2000).
LIE DETECTION USING FMRI
Researchers have used fMRI as a lie detector at the level of individual participants in different ﬁelds. A significant activity in the ventrolateral region of the prefrontal cortex was observed in the context of hidden information even when he individual were not asked to express deceptive responses. (Gamer, Klimecki, & Bauermann, 2009) (Nose, Murai, & Taira, 2009). There is still a need for methodological issues like the effects of simple countermeasure (a method used by liars to defeat lie-detection procedures) to be resolved. The utilization of stratergies that gives access to people’s mental states raises moral issues like privacy concerns. Hence, transfer of imaging technologies to the judicial system is not resonable. Neuroscientists must not ignore the misuse of fMRI as a lie detector which can prompt significant mistakes such as false accusation (Bles & Haynes, 2008) (Haynes, 2008).
NEURAL CORRELATES OF PATHALOGICAL LYING
Lies that are constant and destructive to one’s well being is pathological. Modell conducted a study of pathological lying by using single-photon emission computed tomography (SPECT) and proposd that right thalamic dysfunction may be responsible for the patient’s tendency to lie impulsively (Modell, Mountz, & Ford, 1992). Yang and other authors demonstrated that pathological liars with a past of repeated lying (e.g. fraud) disclosed an increase in white matter volumes in some prefrontal subregions, particularly the orbitofrontal cortex, inferior frontal cortex, and middle frontal cortex. Such a result reveals that prefrontal provides a neurobiological correlate of a deceitful personality (Yang, Raine, & Lencz, 2005).
BRAIN MECHANISMS FOR THE JUDGEMENT OF LYING
With the advancement, research into how the brain evaluates lies is considered important and hence Grezes explored the brain mechanisms involved in detecting deception when observing the nonverbal dynamic behavior of actors and found that when individuals judged the actions as reﬂecting deceptive intention, the amygdala and rostral anterior cingulate cortex were signiﬁcantly activated (Grezes, Frith, & Passingham, Brain mechanisms for inferring deceit in the actions of others., 2004). In a later study, they also found that the amygdala was activated only when the individuals realized they had been deceived (Grezes, Berthoz, & Passingham, Amygdala activation when one is the target of deceit: did he lie to you or someone else?, 2006). Stuss gave more clarification about lesion speciﬁcity and showed that bilateral, particularly right, orbitofrontal lesions impaired patient’s ability to detect deception. Taken together, these previous neuroimaging and neuropsychological ﬁndings raise the liklihood that the limbic and paralimbic systems are responsible for social and affective processing play a critical role in the judgment of lying (Stuss, Gallup, & Alexander, 2001).
In conclusion, deception as a psychological process or a social behavior in itself is a complex phenomenon and can be best interpreted as an integeration of multiple cognitive processes. Technological headways and long studied researches have allowed for the direct assessment of the neural substrates underlying deception. All the evidences lead on the conclusion that the prefrontal cortex plays a pivotal role in human deceptive behavior, although lie detection by fMRI is still problematic based on current evidence.
A substantial amount of research both on deception and neuroimaging techniques underlying deception is yet to be done. Following areas should be further researched to explore the underlying posssibilies under Deception as a psychological phenonmenon.
- Neurobiological basis of genuine (i.e. not experimental) deception.
- A clarification of the conditions that facilitate or inhibit peoples tendencies to be honest or dishonest in a social context should be done to get a better understanding of how the brain determines whether to tell a lie in a complex social interaction.
- Research into neurodevelopmental disorders to get insight into the neural mechanisms underlying deception.
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