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FMRI-based concealed information tests and their vulnerability to countermeasures
Symposia Abstracts / International Journal of Psychophysiology 85 (2012) 291–360
(HR) and enhanced amplitude of the P300 component of the Event Related Potential (P300). In a new meta-analysis we analyzed all four measures described above, in CIT studies that used either the mock crime or the personal item paradigm. Initial results showed an average effect size (d) of 1.74 for SCR, 1.12 for RLL, 0.88 for HR and 2.55 for P300. In addition, the effects of several potential moderating factors were examined and will be discussed. doi:10.1016/j.ijpsycho.2012.06.096
Central and autonomic responses that reflect the intention to conceal in a concealed information test I. Matsudaa, H. Nittonob, T. Ogawaa a National Research Institute of Police Science, Kashiwa, Japan b Hiroshima University, Higashi-Hiroshima, Japan In a concealed information test (CIT), examiners infer whether an examinee has memory of a crime-relevant item from differential physiological responses between crime-relevant and irrelevant items. However, a guilty examinee who has a crime-relevant memory is supposed to conceal it to avoid detection. This intention to conceal may also affect the examinee's physiological responses. In this study, we compared two CIT conditions to examine the effect of the intention to conceal on event-related potentials (ERPs) and autonomic responses. Thirty participants stole two items (one accessory and one electric appliance) through a mock crime. Then the examiner asked them to disclose one of the stolen items. Two CIT conditions were conducted in a counterbalanced order: one CIT was for the stolen item that the participant still had to conceal, and the other CIT was for the stolen but disclosed item. In each condition, 5 items were vocally presented 12 times each with an interstimulus interval of 22 s. ERPs (N2, P3, and late positive potential [LPP]), heart rate, skin conductance, cutaneous blood flow, and respiration were measured simultaneously. For each measure, a Condition (Conceal vs. No secret) × Item (Critical vs. Noncritical) ANOVA was conducted. The N2, P3, heart rate, skin conductance, and cutaneous blood flow differed significantly between the crime-relevant and the crime-irrelevant items in both conditions. In addition, when a participant had the intention to conceal, the LPP amplitude was greater, and the respiratory amplitude was smaller for the crime-relevant item than for the crime-irrelevant items. Some ERP and autonomic responses occurred regardless of the intention to conceal, whereas other responses occurred only when the examinees need to conceal their knowledge. The results suggest that at least two processes underlie the psychophysiological responses during a CIT: a memory-related process and a concealment-related process. The latter process would be indexed by the LPP and by respiration, which may reflect intentional modulation after being conscious of the crimerelevant item.
doi:10.1016/j.ijpsycho.2012.06.097
Face and voice as social stimuli enhance differential physiological responding in a Concealed Information Test W. Ambach Institute for Frontier Areas of Psychology and Mental Health (IGPP), Freiburg, Germany Attentional, intentional, and motivational factors are known to influence the physiological responses in a Concealed Information Test
325
(CIT). Although concealing information is essentially a social action closely related to motivation, CIT studies frequently rely on testing participants in an environment lacking of social stimuli: subjects interact with a computer while sitting alone in an experimental room. We examined the influence of social stimuli on the physiological responses in a CIT. Seventy-one participants underwent a mock-crime experiment with a modified CIT. In a between-subjects design, subjects were either questioned acoustically by a pre-recorded male voice presented together with a virtual male experimenter's uniform face, or by a text field on the screen, which presented the question without face and voice. Electrodermal activity (EDA), respiration line length (RLL), phasic heart rate (pHR), and finger pulse waveform length (FPWL) were registered. The Psychopathic Personality Inventory — Revised (PPI-R) was administered in addition. The differential responses of RLL, pHR, and FPWL to probe vs. irrelevant items were greater in the condition with social stimuli than in the textual condition; the differential responses of EDA did not differ between conditions. No modulatory influence of the PPI-R sum or subscale scores was found. The results emphasize the relevance of social aspects in the process of concealing information and its detection. Attentional demands, as well as the participants' motivation to avoid detection, might be the important links between social stimuli and physiological responses in the CIT.
doi:10.1016/j.ijpsycho.2012.06.098
FMRI-based concealed information tests and their vulnerability to countermeasures G. Ganisa,b University of Plymouth, Plymouth, UK b Harvard Medical School, Boston, USA a
Concealed information tests (CITs) rely on the finding that a salient stimulus (probe), such as an infrequent and meaningful item presented within a series of nonsalient items, produces an orienting response that directs attention to potentially important changes in the environment. By using appropriate nonsalient comparison items (irrelevant items), this response can be used to infer that a person possesses knowledge about a probe but deceptively reports no such knowledge. Individuals with no knowledge about the probe, and who truthfully claim so, will show a much smaller response. Several functional magnetic resonance imaging (fMRI) studies, briefly reviewed in this talk, have documented differences between brain activation to probes and irrelevant items, prompting the creation of companies marketing fMRI-based lie detection services. However, the critical issue of vulnerability of these tests to simple countermeasures had not been adequately addressed until recently. FMRI evidence that fills this research gap will be presented in which participants were trained to use countermeasures by covertly assigning meaning to the nonsalient comparison stimuli in order to reduce the relative salience of the probes. Robust group fMRI differences between responses to probes and irrelevant items were found without, but not with countermeasures. Furthermore, in single participants, concealed knowledge detection accuracy was 100% without countermeasures, using activation in medial and ventrolateral prefrontal cortices, but fell to 33% with countermeasures. These findings clearly demonstrate that fMRI-based concealed knowledge detection measures can be vulnerable to countermeasures, calling for caution before applying these methods to real world situations. doi:10.1016/j.ijpsycho.2012.06.099
(HR) and enhanced amplitude of the P300 component of the Event Related Potential (P300). In a new meta-analysis we analyzed all four measures described above, in CIT studies that used either the mock crime or the personal item paradigm. Initial results showed an average effect size (d) of 1.74 for SCR, 1.12 for RLL, 0.88 for HR and 2.55 for P300. In addition, the effects of several potential moderating factors were examined and will be discussed. doi:10.1016/j.ijpsycho.2012.06.096
Central and autonomic responses that reflect the intention to conceal in a concealed information test I. Matsudaa, H. Nittonob, T. Ogawaa a National Research Institute of Police Science, Kashiwa, Japan b Hiroshima University, Higashi-Hiroshima, Japan In a concealed information test (CIT), examiners infer whether an examinee has memory of a crime-relevant item from differential physiological responses between crime-relevant and irrelevant items. However, a guilty examinee who has a crime-relevant memory is supposed to conceal it to avoid detection. This intention to conceal may also affect the examinee's physiological responses. In this study, we compared two CIT conditions to examine the effect of the intention to conceal on event-related potentials (ERPs) and autonomic responses. Thirty participants stole two items (one accessory and one electric appliance) through a mock crime. Then the examiner asked them to disclose one of the stolen items. Two CIT conditions were conducted in a counterbalanced order: one CIT was for the stolen item that the participant still had to conceal, and the other CIT was for the stolen but disclosed item. In each condition, 5 items were vocally presented 12 times each with an interstimulus interval of 22 s. ERPs (N2, P3, and late positive potential [LPP]), heart rate, skin conductance, cutaneous blood flow, and respiration were measured simultaneously. For each measure, a Condition (Conceal vs. No secret) × Item (Critical vs. Noncritical) ANOVA was conducted. The N2, P3, heart rate, skin conductance, and cutaneous blood flow differed significantly between the crime-relevant and the crime-irrelevant items in both conditions. In addition, when a participant had the intention to conceal, the LPP amplitude was greater, and the respiratory amplitude was smaller for the crime-relevant item than for the crime-irrelevant items. Some ERP and autonomic responses occurred regardless of the intention to conceal, whereas other responses occurred only when the examinees need to conceal their knowledge. The results suggest that at least two processes underlie the psychophysiological responses during a CIT: a memory-related process and a concealment-related process. The latter process would be indexed by the LPP and by respiration, which may reflect intentional modulation after being conscious of the crimerelevant item.
doi:10.1016/j.ijpsycho.2012.06.097
Face and voice as social stimuli enhance differential physiological responding in a Concealed Information Test W. Ambach Institute for Frontier Areas of Psychology and Mental Health (IGPP), Freiburg, Germany Attentional, intentional, and motivational factors are known to influence the physiological responses in a Concealed Information Test
325
(CIT). Although concealing information is essentially a social action closely related to motivation, CIT studies frequently rely on testing participants in an environment lacking of social stimuli: subjects interact with a computer while sitting alone in an experimental room. We examined the influence of social stimuli on the physiological responses in a CIT. Seventy-one participants underwent a mock-crime experiment with a modified CIT. In a between-subjects design, subjects were either questioned acoustically by a pre-recorded male voice presented together with a virtual male experimenter's uniform face, or by a text field on the screen, which presented the question without face and voice. Electrodermal activity (EDA), respiration line length (RLL), phasic heart rate (pHR), and finger pulse waveform length (FPWL) were registered. The Psychopathic Personality Inventory — Revised (PPI-R) was administered in addition. The differential responses of RLL, pHR, and FPWL to probe vs. irrelevant items were greater in the condition with social stimuli than in the textual condition; the differential responses of EDA did not differ between conditions. No modulatory influence of the PPI-R sum or subscale scores was found. The results emphasize the relevance of social aspects in the process of concealing information and its detection. Attentional demands, as well as the participants' motivation to avoid detection, might be the important links between social stimuli and physiological responses in the CIT.
doi:10.1016/j.ijpsycho.2012.06.098
FMRI-based concealed information tests and their vulnerability to countermeasures G. Ganisa,b University of Plymouth, Plymouth, UK b Harvard Medical School, Boston, USA a
Concealed information tests (CITs) rely on the finding that a salient stimulus (probe), such as an infrequent and meaningful item presented within a series of nonsalient items, produces an orienting response that directs attention to potentially important changes in the environment. By using appropriate nonsalient comparison items (irrelevant items), this response can be used to infer that a person possesses knowledge about a probe but deceptively reports no such knowledge. Individuals with no knowledge about the probe, and who truthfully claim so, will show a much smaller response. Several functional magnetic resonance imaging (fMRI) studies, briefly reviewed in this talk, have documented differences between brain activation to probes and irrelevant items, prompting the creation of companies marketing fMRI-based lie detection services. However, the critical issue of vulnerability of these tests to simple countermeasures had not been adequately addressed until recently. FMRI evidence that fills this research gap will be presented in which participants were trained to use countermeasures by covertly assigning meaning to the nonsalient comparison stimuli in order to reduce the relative salience of the probes. Robust group fMRI differences between responses to probes and irrelevant items were found without, but not with countermeasures. Furthermore, in single participants, concealed knowledge detection accuracy was 100% without countermeasures, using activation in medial and ventrolateral prefrontal cortices, but fell to 33% with countermeasures. These findings clearly demonstrate that fMRI-based concealed knowledge detection measures can be vulnerable to countermeasures, calling for caution before applying these methods to real world situations. doi:10.1016/j.ijpsycho.2012.06.099