Forensic neuropsychologists study congenital brain structure and the chemical imbalances that have a negative effect on social behavior. Some psychologists believe that aggression is a biochemical reaction that stimulates certain neurotransmitters in the brain that innately display predatory aggression in humans. The relationship between these neurotransmitters and the chemicals that stimulate them is what forensic neuropsychologists focus on in order to understand the genesis of criminal behavior.
Forensic neuropsychologists apply assessment techniques to determine the reasons behind criminal behavior and aggressive actions. Psychological tests, intelligence tests and tests that reveal the actions that raised the biochemical activity that manifests as isolation, fear and aggressiveness, are used to identify people with criminal behaviors. A heightened level of aggressiveness can be considered mental illness, but a forensic neuropsychologist is able to differentiate between premeditated actions and actions that are the result of a chemical brain disorder that cannot be controlled.