4. Influential Factors affecting Deception
4.1Spontaneous Vs Memorised Lies
There are various types of lie, yet the majority of studies underestimate the importance of this and assume that there is only one type, thus the difficulty in transference between laboratory and real-life scenarios. It is feasible that different neural systems are responsible for the execution of these different [S1]lies because a lie memorised or rehearsed prior to questioning is retrieved solely from memory (Ganis et al., 2003). Spontaneous lies are distinguishable from this as the brain retrieves stored episodic memory (activation of the anterior PFC and precuneus) and semantic knowledge (activation of the VLPFC and frontoparietal network) (Ganis et al., 2003; Domagalik et al., 2012) to construct the lie. It is easier to generate spontaneous isolated lies because they do not fit within a story, removing the need to cross-reference data to ensure that the lie is believable. On the other hand, memorised lies as part of a coherent story are easier to construct because retrieval cues help an individual to remember their lie. This requires working memory because information is stored, remembered, and referred to later (Ganis et al., 2003).
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Ganis and colleagues investigated the neural patterns during spontaneous isolated lies (SI) and memorised scenario lies (MS). Participants provided two real scenarios and one memorised lie based on one change to a true scenario, and during scanning they were asked questions to exercise their memory to refer to truth or memorised lie stories, or spontaneously lie when asked a question they were unprepared for. The main findings showed the ACC extending into the left premotor cortex, the left precentral gyrus, the right precentral/postcentral gyrus and the right cuneus more strongly activated in the SI condition than the MS (SI>MS). In contrast, only the right anterior middle frontal gyrus was more activated in the opposite condition (MS>SI). From this study, the authors concluded that both lie conditions yielded greater activation than the truth condition and greater activation was observed for SI lies than MS lies (Ganis et al., 2003).
An extension to this study by Morgan et al., 2009 provides supportive evidence that different cognitive processes are required to generate and execute different lies. Their study was based on individuals differing in their ability to efficiently retrieve stored information and monitor mental conflict, and the investigators used initial response times (IRT) to determine when individuals were lying. Generally, IRT are longer during deceptive responses compared to truthful responses, however, contradictory studies found prepared lies had a shorter IRT than the truth (see Morgan et al., 2009). Unlike Ganis et al., 2003, Morgan and colleagues carried out individual analysis, and results showed participants taking less time to lie using their memorised stories than to tell the truth, possibly because due to rehearsal allowing easier and quicker access to it.
The use of countermeasures during lie detection testing is a niche area of research, and Ganis et al., 2011 is the first and only study to date solely focusing on this influential factor. Defendants in real-life lie-detection scenarios, facing the risk of imprisonment, are expected to have the motivation to successfully confuse deception detectors by employing countermeasures, such as carrying out a mathematical calculation prior to answering a question. Studies fail to integrate the use of countermeasures into their research, despite them limiting the accuracy of lie detection (Ganis et al., 2011), and only one study questioned participants post-scanning to see if they had attempted countermeasures (Kozel et al., 2005). Ganis and colleagues observed the effect of countermeasures on activated neural regions using three test conditions: (i)-no knowledge, (ii)-concealed knowledge and (iii)-countermeasures. In the latter condition, participants performed a given covert countermeasure prior to lying when answering questions about their date of birth, and idiographic analysis showed activation in the anterior mPFC and VLPFC. Deception without the use of countermeasures was successfully identified in all participants, but accuracy of 100% notably reduced to 33% during the countermeasure condition, with deceptive responses incorrectly classified as the truth due to a decrease in significant differential activation between the two responses. These findings provide additional evidence that caution is needed before applying imaging techniques to the real-world as they may be vulnerable to countermeasures, rehearsed or otherwise, which may mislead lie detectors. Moreover, suspects are likely to rotate deceptive and truthful responses if the police interviewer is expecting them to lie, and this can affect results (Ganis et al., 2011). Finally, the question order would be unknown to defendants, so they would have to constantly remember the memorised lies and countermeasures whilst answering questions truthfully.
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Anyone intending to use countermeasures is expected to have prepared and practised them first; therefore in this study subjects rehearsed their countermeasures prior to scanning. This may not be the case if [S2]an individual is arrested and interviewed immediately; hence investigation into the comparison of prepared and spontaneous countermeasures should be undertaken. Another limitation was Ganis et al., 2011 instructing participants on the motor countermeasures to use, and participants may not have felt comfortable and relaxed carrying out forced actions of moving their left index finger, for example. In comparison, the experimental paradigm by Lee et al., 2002 stimulates a more realistic lying situation as participants devised their own strategies for lying, yielding strong external validity.
4.3Antisocial Personality Disorder (ASPD)
The majority of studies highlighted in this paper focus on healthy subjects within a small sample who are of a younger age, often from University, and who are probably unskilled at lying due to lacking a history of serious offences. Being guilty of crimes such as theft, offers a far smaller punishment than for serious crimes, therefore reducing the incentive for skilled lying. Thirteen studies, amongst others, screened subjects prior to testing to ensure they were healthy and had no underlying neurological disorders (table 1). Studies with entirely healthy subjects are not true representations of the sample population, and it is unlikely that everyone screened to determine deception in a real-life scenario would be healthy, and this is based on several surveys reporting that a large number of prisoners suffer with mental illness or brain damage (Merikangas 2008). It could be hypothesised that some major criminals are likely to be mentally unstable, or have a stronger desire to be deceitful, and Spence et al., 2004 suggested that psychopaths have the skills to potentially mislead a lie detector as they are experienced liars with suspected superior executive brain functions.
Prior to 2013, activation of neural correlates in individuals with antisocial personality disorder (ASPD) was unclear. A core feature of ASPD is deceit (Kozel et al., 2004b), making them more likely to be skilled at lying, and links between criminal activity and ASPD have already been established (Tang et al., 2013). Whilst a recent review paper encompassed a number of factors influencing fMRI lie detection, it omitted the neurobiological effect of disorders such as ASPD (Rusconi et al., 2013). In 2013, deception detection was observed amongst thirty-two young offenders with ASPD, who were categorised into three groups depending on their capacity for deception. Subjects selected three pictures from a set of ten before being allocated to “true”, “inverse” or “lie” conditions. Following questioning during scanning, results of the “lie-rest > true-rest” contrast revealed significant activation in the bilateral DLPFC extending into the MFG, left inferior parietal lobule, supramarginal gyrus, and bilateral ACC, with the opposite contrast revealing no significant activation (Jiang et al., 2013). Activation in the prefrontal and parietal regions support results from previous fMRI studies on healthy subjects (Spence et al., 2001; Langleben et al., 2002; Lee et al., 2002; Ito et al., 2011, 2012) confirming that ASPD generates activation in similar regions to someone without ASPD during deception. However, this is only one disorder tested, and the results must not be assumed or transferred to other disorders.
The accuracy of results from previous fMRI lie detection studies is further thrown into question, as Jiang and colleagues were the first to show that as the capacity of an individual to lie increases, the significant activation of the aforesaid regions decreases. Consequently, great caution should be applied to detecting lies in persons that are skilled or use countermeasures in lying because activation in the suspected brain regions may not be seen, even if they are lying. Activation during the truth condition in the left middle frontal gyrus, right medial frontal gyrus, left inferior parietal lobule, and left middle frontal gyrus remained relatively constant across the three capabilities of lying (2=severe liar, 1=mild liar, 0=non-liars), however, activation during the lie condition decreased by approximately 50% between non-liars and severe liars across all four brain regions (figure 3). Although the same brain regions activate [S3]in ‘healthy’ subjects and individuals with ASPD, they may not be activated to the same extent, as offenders with ASPD have a greater capacity for lie-telling and they are capable of inhibiting PFC activation during deception (Jiang et al., 2013). Finally, it should be considered that mental illness, psychological traits or brain damage could have a profound effect on brain activity and fMRI results. Subjects with lesions to the DLPFC, an area activated during anti-saccade movements, have been found to frequently make mistakes during anti-saccade paradigms (Nyffeler et al., 2007); therefore any damage to the DLPFC in subjects participating in deception studies may also affect fMRI results, and could potentially be true for other brain regions.
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These are only three areas where research is in its infancy to determine the extent that they influence deception detection, and until clear understanding is established, deception results should not be used to support criminal investigations.
Fig. 3 – Key activated brain regions observed following subjects lying about three pictures which they had selected. The four brain regions seen to be activated during the lie > truth condition are: (a,b) Right medial frontal gyrus, (c,d) Left middle frontal gyrus, (e,f) Left inferior parietal lobule, (g,h) Left middle frontal gyrus. The differential activation is far smaller between the lie (blue) and truth (red) condition when the subject is a severe liar compared to being unskilled and having no capacity to lie. (2=severe liar, 1=mild liar, 0=non-liars)
(See Jiang et al., 2013. Available at: http://beta.orionshoulders.com/Resources/articles/2_1_Jiang%20%20W.%3B%20Liu%20%20H.%3B%20Liao%20%20J.%3B%20Ma%20%20X.%3B%20Rong%20%20P.%3B%20Tang%20%20Y.%3B%20Wang%20%20W.%20(2013).pdf. Last accessed on: 26th February 2014)
[S3]Does this make sense?? Become activated?