Role of Cognitive Neuroscience in Forensic Psychology

Deception detection is an essential aspect of Forensic Psychology. It is an important scientific issue that involves investigating the psychological and physiological changes in individuals while they lie. Experts in the field work hard to develop effective methods to detect deception. These deception detection methods are essential in criminal investigations, airport security, terrorism, etc. One of the oldest approaches to detect deception is Polygrpah, which studies changes in the physiological responses of the individual. However, numerous studies have indicated that lying is a complex cognitive process that involves an exchange of information between neurons in multiple brain regions.

Studies using these techniques have highlighted that the neural mechanism involved in lying is different than truth-telling. Other studies have revealed that deception is a complex cognitive process consisting of various perceptive and cognitive components, including inhibition control, task switching, greater cognitive control, working memory, etc. Researchers analyse these intricate mechanisms to understand and uncover how we deceive others.

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The studies in this field started with investigating the distinct components of event-related potential or ERP based on brain cognition. Picton became the first to discover the P300 components of evoked potential, which are triggered by rare stimuli. He further demonstrated that these ERP components are related to memory and thinking and reflect the brain’s cognitive processes. Several studies revealed that the P300 component is more likely to be induced by familiar objects than new things. However, as the research progressed, scientists realized that the rate of false positives using the P300-based deception detection technique is significant to be ignored, leading them to use non-linear analysis techniques.  Researchers have recently started analyzing the EEG data for deception detection studies using connectivity analysis. Brain regions communicate and coordinate their activity through the synchronization of neural oscillations. These oscillations represent the rhythmic patterns of electrical activity in the brain. When different regions synchronize their oscillatory activity, it suggests that they are working together to process information or perform a particular cognitive task. The question is, why is this synchronization necessary? There are some reasons why different brain regions need to work together.

1. Synchronization helps increase the signal-to-noise ratio in neural signals.
2. Synchronization facilitates efficient communication and coordination between brain regions.
3. Different patterns of synchronization are associated with specific cognitive processes. Synchronization influences the timing and strength of neural responses, impacting cognitive functions such as perception, attention, and memory.
4. Synchronization is a fundamental component of brain network dynamics. It enables the formation of functional networks, where brain regions work together to perform specific functions.
5. Synchronization is crucial for adaptive behavior. It helps the brain respond to changing demands, such as processing sensory information or executing motor actions, by dynamically coordinating different regions.

Researchers have been trying to study the brain regions that synchronize when individuals lie. One EEG study revealed that the connectivity is increased between the upper and middle frontal gyrus in the left hemisphere when the individual lies.

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The role of Frequency bands

There are five major frequency bands: delta, theta, alpha, beta, and gamma. These frequency bands have their unique functions. Alpha and beta waves were discovered by Berger in 1929. In 1938, Jasper and Andrews discovered gamma waves, and delta and theta waves were discovered by Walter in 1936. First, let us understand the general function of these waves-

Delta waves occur between 0.5 and 4.0 Hz. They are the least frequent yet have the biggest amplitude of the others. They happen posteriorly in youngsters and frontally in adults. Deep sleep is mostly linked to these waves.

Theta waves have a frequency range of 4 to 8 Hz. Typically, theta waves are seen in young children. However, similar waves are noticed in older children and adults during meditation, drowsiness, or arousal. These waves could happen anywhere and have nothing to do with current responsibilities. Theta waves in excess could signify aberrant activity.

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The frequency range of alpha waves is 8–13 Hz. Dr Hans Berger identified these waves, known as alpha waves since they were the first ones to be found (first waves). Wakefulness, shutting one’s eye, effortless alertness, and inventiveness correlate with alpha waves. These waves typically manifest in the back of the head and are larger than the occipital regions.

The frequency range of beta waves is 14–26 Hz. These waves are unique to healthy adults and are also referred to as sensory-motor rhythm; they are associated with active attention, active thinking, solving complex issues, or focusing on the outside world. The frontal and central regions are where rhythmical beta waves are most commonly felt. Beta waves often have a low amplitude and are less than 30 μV.

Gamma waves are found above 30 Hz (up to 100 Hz). They aid in figuring out how various populations of neurons are bound together. In the human brain, they occur infrequently. They only occur during cross-modal sensory processing, which is blending multiple senses like sight and sound.

These frequency bands are also important from the point of view of studying deception. For example, the Delta band plays an important role in human attention. When a person is lying, the brain will allocate all the resources to the suppression of truthful information and the exposure of false information. Theta band is caused by working memory activity. Researchers in the field of deception detection are still trying to figure out the role of theta during lying. Alpha oscillations are important in suppressing distracting input. Studies have revealed that an increase in the alpha band results in functional inhibition. Studies in the area of deception detection have demonstrated that the beta band is involved in cognitive inhibition.

The studies in this field have improved our knowledge of how individuals lie and what happens in their brains. However, more research is required to make better and more informed judgments.

References

1. Wei Et Al.: Analysis Of Weight-Directed Functional Brain Networks In The Deception State Based On Eeg Signal
2. https://eprints.soton.ac.uk/416828/1/Methods_in_Cognitive_Neuroscience_A_primer_for_Forensic_Psychologists.pdf

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