Biological Explanations of Criminal Behavior: Forensic Psychology Study Guide

Overview of Biological Explanations for Criminal Behavior

• Researchers have identified a significant correlation between brain health and incarceration.
• It is a documented fact that there is a greater percentage of individuals in jail with an acquired brain injury (ABI) compared to the general population.

Anatomy of the Brain: The Four Lobes

The brain is divided into four primary lobes, each responsible for different physiological and cognitive functions:

• Frontal Lobe: Responsible for mental actions and executive functions.
• Temporal Lobe: Involved in processing sensory input.
• Parietal Lobe: Involved in integrating sensory information.
• Occipital Lobe: Primarily responsible for visual processing.

The Frontal Lobe and Executive Functioning

The frontal lobe (specifically the pre-frontal cortex) is the center for higher-order cognitive processes known as executive functions. These include:

• Planning and Problem Solving.
• Motivation and Judgment.
• Decision Making.
• Impulse Control.
• Social Behavior and Personality.
• Memory and Learning.
• Reward processing and Attention.

Implications of Frontal Lobe Damage or Underdevelopment:

• If this area is damaged or underdeveloped, an individual may struggle to think through the consequences of their actions.
• It leads to difficulties in controlling impulses.
• Affected individuals are more likely to respond to situations with violence, react aggressively when angry, or succumb to peer pressure regarding illegal activities (e.g., agreeing to steal).

Case Studies in Childhood Head Trauma and Serial Crime

A notable commonality among several infamous serial killers is the history of significant head trauma during childhood. Collectively, the following four men were convicted of murdering a total of $65$ people:

• Richard Ramirez ("The Night Stalker"):
  • At age $2$, he sustained a head injury when a dresser fell on him, necessitating $30$ stitches.
  • At age $5$, he was knocked unconscious by a swing in a park. This injury led to epileptic seizures that persisted until his teenage years.
• John Wayne Gacy ("The Killer Clown"):
  • At age $6$, he was beaten unconscious by his father with a broomstick.
  • At age $11$, he was struck in the head by a swing. This resulted in blackouts that were not diagnosed until he was $16$ and were further complicated by a congenital heart arrhythmia.
• Jeffrey Dahmer: Listed as having suffered childhood head trauma.
• Ed Gein: Listed as having suffered childhood head trauma.
• Alexander Pichushkin (Russian Serial Killer):
  • Known as a sociable child until he was struck in the head by a swing, which damaged his frontal cortex.
  • He famously aimed to kill $64$ people, representing the number of spaces on a chessboard.

The Amygdala and Emotional Regulation

The amygdala is a structure located within the brain (associated with the hippocampus) that regulates emotions.

• Dysfunction: If the amygdala is damaged, atypical in size, or overactive, it may be triggered more quickly than in a healthy brain.
• Psychopathy Connection: An underactive amygdala is often found in individuals assessed as psychopaths. This leads to:
  • Difficulties in processing emotions.
  • A distinct lack of remorse or empathy for victims.
  • Significantly higher rates of aggression.

Hormonal Factors and Demographic Statistics

• Prison Demographics (Australia, June $2020$):
  • Out of approximately $40,000$ people in Australian prisons, $92\%$ are male. (It is a common misconception that the figure is as low as $62\%$).
• The Role of Testosterone:
  • Testosterone is a male sex hormone secreted by glands in the endocrine system and transported via the bloodstream.
  • Research indicates that testosterone can activate the amygdala and trigger the "fight-flight-freeze" response.
  • High levels of testosterone can override the prefrontal lobe's ability to maintain rational decision-making and impulse control.

Neurocriminology Research: Adrian Raine ($2016$)

Adrian Raine, a pioneer in the field of neurocriminology, investigated the biological differences between murderers and non-murderers.

• Study Methodology:
  • Raine compared $41$ murderers (who pleaded not guilty by reason of insanity) against a control group of $41$ non-murderers.
  • The murderers consisted of $39$ males and $2$ females.
  • He used Positron Emission Tomography (PET) scans, an imaging technique that allows researchers to observe the brain while it is active.
• Key Findings:
  • Frontal Lobe Activity: Murderers showed significantly less activity in their prefrontal lobes compared to the control group.
  • Amygdala Abnormalities: Murderers exhibited asymmetrical abnormalities. They had reduced activity in the left amygdala but greater activity in the right amygdala.
• Visual Evidence: PET scans (such as Figure $8.2$) use colors like red and yellow to indicate high functioning. In Raine's study, those in the control group showed widespread high-functioning areas in the prefrontal cortex, while the murderers' scans showed a marked reduction in these areas.

Academic Application: Explaining Violent Crime

When explaining how the brain is responsible for violent crime, two primary biological variations are cited:

1. Undersized/Underactive Amygdala: This biological condition may be an underlying cause of crime because it accounts for a lack of empathy or remorse, which are necessary inhibitors to committing violence.
2. Damage to the Pre-frontal Cortex: This impairs the cognitive capacity to control impulses. For example, damage here might lead an individual to commit a murder during a minor verbal dispute over property because they cannot regulate their immediate aggressive reaction.

Key Terminology Summary

• Amygdala: A structure in the brain (near the hippocampus) responsible for regulating emotions.
• Pre-frontal Cortex: The area of the brain responsible for executive functions, including planning, impulse control, and rational decision-making.
• PET Scan: A brain imaging technique used to observe the brain's activity levels through metabolic processes.
• Hormones: Chemical messengers secreted by the endocrine system into the bloodstream.