The Psychology of Crime and the Prefrontal Cortex
Prefrontal brain damage can contribute to impulsive behaviors.
Posted September 2, 2025 | Reviewed by Abigail Fagan
Much criminal behavior derives from logical, if not laudable, sources. A wonderful example of this was seen in the old Bob Newhart television show. Newhart, playing a clinical psychologist, leans across a prison interview table and addresses a convicted thief. “Why,” asks Newhart with considerable clinical elan , “do you steal things?”
The thief, imitating Newhart’s posture, demeanor, and vocal inflections, leans across the table toward him. “Because,” says the thief, “I want them.”
This memorable scene may encapsulate much of what there is to be understood about crimes for gain. The criminal obtains money or property. It's also true that there are many other types of gain than the monetary or the material, and a variety of crimes may be committed for gain in the realms of sex , power, or revenge for real or imagined offences.
Yet many crimes appear to make no sense in terms of gain for the perpetrator, and may in fact prove actively disadvantageous for that individual. Various forms of vandalism, punching people out in bars, impulsive acts of road rage or assaults on fellow passengers in overcrowded aircraft; all achieve nothing for the perpetrator except the prospect of criminal prosecution, civil suits, and prison sentences in the worst cases.
So why would anybody do these things?
This is a very complex question, and we obviously won’t be able to answer it comprehensively here. However, in this first post of three on major psychological influences on crime, we will focus on a factor that at least correlates with psychological processes involved in crimes of impulse: damage to the prefrontal areas of the brain.
The brain has evolved, and human beings exist with the consequences of that evolution. Human beings possess a highly developed neocortex . The prefrontal parts of that neocortex, among many other important functions, help us to inhibit inappropriate behaviors that may arise from areas of the brain which, especially in the subcortical brain, we share with other mammals that possess less neocortex, and even with reptiles and other creatures that don't possess a neocortex at all.
Creatures without a human neocortex are much more likely to give in to their subcortical impulses than are humans. Having been personally involved in studies of Russell’s Viper (Carr et al., 1982), a snake which tends to strike violently and venomously at practically anything that moves; of Everglades alligators with whom I have no intention of ever sharing a stagnant pool; and of monkeys who seemed to delight in the flinging of their own feces, and who were capable of a phenomenon called ballistic urination that I'd rather not even talk about, I can personally attest to the fact that the absence of a human prefrontal neocortex can contribute to some rather nasty behaviors which we would term criminal if they occurred in a human. I still have yellow stains in one of my lab coats, which will never wash out.
Fortunately, most human beings are not very big on ballistic urination or on the joys of feces-flinging. However, when sufficiently aroused by stress , we enter the human fight-or-flight response, in which blood-borne resources are diverted from the brain, especially from the prefrontal cortex, to the needs of our sub-cranial muscles. Under these circumstances, our prefrontal cortices tend to go at least partially off duty, allowing us to engage in a variety of disinhibited behaviors generally regarded as suboptimal in most polite society; these may include hypervigilance to offence and hyperreactivity in dealing with it; increased levels of irritability and aggressiveness; and failures to inhibit impulses, even violent impulses which may have major legal consequences for us at later times (e.g., Artwohl, 2019; Grossman, 1995; Sharps, 2022a,b; Sharps, 2024).
So, in the normal human fight or flight response, we may become more impulsive under stress, but what happens in cases in which the prefrontal cortex has actually been damaged?
The relationship of prefrontal damage to impulsive behavior across cases is of course correlational; specific causal linkages are very difficult to establish in this realm. However, we have a wide variety of historical examples in which prefrontal impacts are at least dramatically associated with later impulsive behavior. Take the case of general George S. Patton, an acknowledged military genius who was nevertheless sufficiently disinhibited that he slapped the living hell out of two PTSD victims in military hospitals, cursed and swore not only in battle but also in front of media and even commissions of military chaplains, and publicly insulted other field commanders, including his own commander, General Dwight D. Eisenshower.
Why would a military genius engage in these personally destructive behaviors? We can't be certain, but we do know that Patton, a lifelong athlete , would today be called an extreme athlete and equestrian. He suffered a variety of tremendous impacts to his skull, especially to the areas of that skull housing the prefrontal cortex; and much of his impulsive behavior was observed in the aftermath of these neurological events (e.g., Sharps, 2022a).
The same is true of General George Armstrong Custer. Custer was always impulsive, but after being deposited very firmly on his head after he shot his own horse during a buffalo hunt, his impulsive behaviors multiplied dramatically, culminating in the series of errors that resulted in his death at the Little Bighorn (e.g., Sharps, 2022a). This may illustrate the phenomenon of positive feedback; impulsive behaviors, which damage the prefrontal cortex, may result in even more impulsive behaviors, which result in even more damage, and so on.
Although entirely correlational, these and other historical examples may help to illustrate the known fact that prefrontal cortical damage may relate to the kinds of impulsive behaviors that may result in an essentially suicidal charge at the Little Bighorn, or in a bar fight when our football team loses. Damage to the prefrontal cortex can contribute to impulsive behavior, which can contribute to crime, even to crime without gain. This obviously does not excuse the crimes in question, but it may help forensic psychologists in understanding how they arise.
Artwohl, A., & Christensen, L. 2019. Deadly Force Encounters (2nd ed.) LWC Books.,
Carr, J., Maxion, R., Sharps, M.J., Weiss, D., O'Connell, B., & Chiszar, D. 1982. Predatory Behavior in a Congenitally Alingual Russell's viper (Vipera russelli). 1. Strike Induced Chemosensory Behavior. Bulletin of the Maryland Herpetological Society, 18, 196-204.
Grossman, D. (1995). On Killing. Boston: Little, Brown & Co.
Sharps, M.J. 2022a. Processing Under Pressure: Stress, Memory, and Decision-Making in Law Enforcement (3rd ed.).Park City, UT: Blue 360 Media.
Sharps, M.J. (2022b ). Thinking Under pressure: A Guide for Firefighters and the Fire Service . Amazon.
Sharps, M.J. (2024). The Forensic View: Investigative Psychology, Law Enforcement, Space Aliens, Exploration, and the Nature of Madness. Amazon.
Share this post Facebook Bluesky Linkedin Email
There was a problem adding your email address. Please try again.
By submitting your information you agree to the Psychology Today Terms & Conditions and Privacy Policy
Matthew Sharps, Ph.D., professor of psychology at California State University, Fresno. He researches forensic cognitive science among other related areas.
Get the help you need from a therapist near you–a FREE service from Psychology Today.
This article is part of the Bringwise Psychology Journal — daily insights on human behavior, mental health, and personal growth.