Transcript Slide 1
ERP and fMRI Research in the Detection of Deception Jennifer M. C. Vendemia Michael Schillaci - Robert Buzan - Eric Green - Scott Meek Organization • • • • Theoretical Research with ERPs fMRI in 5 seconds Current Deception Research with fMRI Techniques combining multiple methods Amplifier Buzz Scalp, Skull High Impendence Random Brain Activity Muscle Aspects of deception in the ERP P3a: An early attention related component with an anterior distribution and positive deflection. Occurs when one switches tasks such as from telling the truth to telling a lie. P3b: A late component that is related to decision making, workload, inhibition, and attention, and context updating. N400: A component that occurs when what we’ve heard, said, or seen does not match the contents of our semantic (and possibly) episodic memory. Anterior distribution, negative deflection 0 250 500 750ms ERPs: The Signal-Noise Approach Signal: Brain wave associated with deception • Several potential waveforms are studied • The most consistent is the P300 evoked in an oddball paradigm with concealed information Noise: Every other signal generated by the human brain The Signal-Noise Approach has Historically Proven Inadequate for BOTH Polygraph and ERPs • Reliability Both measures deliver consistent results across repeated tests • Validity But NEITHER measure has been experimentally validated – They measure something, but not necessarily deception The Signal-Noise Approach has no History with fMRI • Reliability Few consistent findings • Validity No validity with reliability Functional MRI This technique allows us to watch the human brain in action. Functional MRI • An MRI scanner can detect the magnetic change as blood flow increases in certain parts of the brain. • We can use this to determine which parts of the brain are most active. Functional MRI • Example: ask a person to move their eyes S1: sensation M1: movement Activated Parts of the Brain Current Research in fMRI: Regions of Activation sited in Bhaat et al (in press) Area 9, 10 VLPFC Area 32 Sensory Motor Strip Area 8 Area 21 Area 17 Caudate Cerebellum *Additional regions: Hippocampal gyrus, left inferior parietal Individual Trials fMRI studies Variability in fMRI Approaches • Within Subject Noise – – – – – – – – – • Subject movement Respiratory, cardiac artifacts Scanner instability Attentional modulation Inconsistent cognitive strategy Learning effects Drugs and medications Anxiety Countermeasures Between Subject Noise – – – – – Consistent differences in factors related to within subject noise Anatomic variability Cytoarchitectonic variability Variability in venous drainage patterns Differences in hemoglobin concentrations • Between Paradigm Noise – – – – Inconsistent definition of the type of deception DIfferences in the rate, number, and type of stimuli presented Differences in the type of memory to which the participants deceive Differences in reward/punishment scenario Incidental Measurement Differences Example paradigm differences • Spence, Farrow, Herford, Wilkinson, Zheng, and Woodruff (2001): directed lies to episodic memory • Langleben, Schroeder, Maldjian, Gur, McDonald, Ragland, O’Brien, and Childress (2002): directed lies in a digit recall type task with cards • Lee, Liu, Tan, Chan, Mahankali, Feng, Hou, Fox, and Gao (2002): Feigned memory impairment to digit span and autobiographical memories • Ganis, Kosslyn, Stose, Thompson, and YurgelunTodd (2003): Planned lies vs. spontaneous lies to long latency episodic information • Kozel, Padgett, and George (2004): Planned lies to recently short latency episodic information • Faro, Mohamed, Gordon, Platek, Williams, and Ahmad (2004): Planned lies to short latency episodic information Deception is a complicated sociodynamic cognitive process • It is possible that deception is not the result of a unique structure or system within the human brain • Rather it is the result of several sub-processes that are also recruited during other sociodynamic cognitive processes (like lecturing) Conclusions from MRI Studies • Motivation: Kozel, Langleben, Phan – Orbitofrontal activation only present in Kozel • Autobiographical Memory: Ganis, Lee, Spence – Temporal activation present only in LEE • Weighing of multiple information sources—all studies – Prefrontal cortex: Lee, Ganis, Kozel, Faro • Resource allocation, attention switching, response conflict – all studies – Lee, Langleben, Ganis, Kozel, Faro, Spence, Phan • Regions of confusion – Cuneus, cerebellum Conclusions • These technologies are not ready for practical application • The issues that limit the utility of ERP and fMRI have nothing to do with the equipment • The major problems all revolve around the supporting science • The science is currently in its infancy, and has thus far had a troubled development