Last updated 7th July, 2018
The Origins of Criminal Behavior
n the 18th century popular belief was that criminal behavior was entirely biological in cause. In 1871, a psychiatrist and prison doctor by the name of Cesare Lambroso was working in an asylum for the criminally insane. Lambroso made a discovery that year that led him to a controversial theory. This theory is said to be the foundations of the idea that the brains of criminals, particularly violent and aggressive criminals, are different and these differences can be seen and measured.
While performing an autopsy, Lambroso found an “unusual indentation” at the back of a prisoner’s skull. From this, he inferred that deformities of the brain were the cause of criminal behavior. Building on the theory of the phrenologists of that time, he claimed physical characteristics such as large jaws and sloping foreheads make criminals stand out from the crowd.
Lambroso was shouted down when he announced his theories and over the years amended his estimations. Towards the end of the 18th century, Lambroso stated he believed 40% of the total criminal population had innate biological factors determining their criminality. In other words over one-third of the population were born criminal.
He continued to modify his theories giving more weight to the physical and social environment as factors involved in the development of an offender. By 1889 his estimates were 33% of the population were born criminal and he highlighted the importance of social circumstances which may encourage such biological abnormalities.
In our modern-day most of the phrenologist theories have been dismissed, however, the question over whether criminals are born or made has never entirely disappeared. The advancement of brain imaging technologies has opened the door for a wealth of research targeting convicted criminals in order to examine their brains more closely.
Magnetic Resonance Imaging (MRI) is able to obtain images of a living brain through a magnetic field scanner and functional MRI uses the same technology to measure blood flow to different parts of the brain while the person being scanned is carrying out a task such as listening to sounds or viewing images. Before such technologies were developed, taking a look inside the brain of an individual was impossible to do while they were alive. While examining a brain at autopsy may show any obvious abnormalities in physical appearance and structure, what it cannot do is give an idea of how that brain functioned and operated while the person was alive.
The use of functional MRI can be particularly revealing when asking an individual to carry out tasks while their brain is being monitored and respond in some way to certain stimuli, generally by pressing a button. What this does is allow neuroscientists to gather data about which part of the brain is responding and when, how fast it responds or when another section of the brain becomes activated and deactivated.
When considering criminal behavior, such testing can be used to directly compare the brain activity of criminals against the brain activity of non-criminals when they are carrying out the same tasks, enabling any differences to be spotted and analyzed.
Predicting Criminal Behavior Using Brain Imaging
Research scientists have been able to create experiments designed to test an individual’s brain functioning including their emotional responses, decision-making abilities, and impulsivity. The results obtained from these types of tests are automatic responses which an individual cannot control willingly, therefore they provide a more reliable measure comparatively to self-reports regarding feelings and emotions under particular circumstances.
Neuroscientists from the University of New Mexico conducted a neuroimaging study with 96 adult offenders in a New Mexico prison who were within four years of their release. Eyal Aharoni and his colleagues wanted to see whether the offender’s brain scans could be used to predict the likelihood of the prisoners re-offending in the future.
Working with the Mind Research Network the researchers were able to take a mobile fMRI scanner into the prison in order to carry out the testing with the prisoner group. They scanned prisoners’ brains while they were undertaking tasks which involved making quick decisions and trying to stop themselves reacting impulsively.
In a ‘go/no-go’ task, subjects watched a screen in front of them and were asked to react to what was displayed.
• When an ‘X’ appeared on the screen, they were to press a hand-held button (a go trial)
• When a ‘K’ appeared they were not to press the button (no go trial)
• In order for their response to count they had to respond to the go trials in less than one second
In this way, the test was focusing on the participant’s impulse reactions and decision-making abilities, as well as the ability to resist when the K appeared on a no-go trial.
Go trials were presented 84% of the time, essentially priming the individual completing the task. As these trials appeared more often, the prisoners came to expect them on each trial. Therefore, when a K appeared instead, they had to restrain themselves from the impulse reaction of pressing the button like they had been doing on most other trials.
The more impulsive a person is, the more difficult they are going to find not pressing this button. Researchers carried out this experiment with both a group of convicted criminals from the prison and a group of non-criminals, in order to make a comparison between the two groups.
They found that the convicted criminals’ group were more impulsive than the non-criminal control group. The prisoners tested found it much harder to resist pressing the button during the K no-go trials making significantly more mistakes than the control group.
This research and similar studies are important as they highlight some of the areas that those engaged in criminal behavior may struggle with. It has been suggested impulsiveness is one of the factors involved in criminal behavior, where even if a person realizes the potential negative consequences of committing a crime, once they have started they find it difficult to stop.
There are many criminals who have already been caught for carrying out a crime and sent to prison as their punishment, however, after release, they either continue their criminal activities or in some cases, increase the severity of their criminal behavior.
Andrew Dawson is one such example. A man given a life sentence in 1982 for the brutal murder of 91-year-old Henry Walsh in Lancashire, England, he was released from prison in 2010. Within weeks of leaving his prison cell, he had gone on to murder two more innocent individuals, John Mathews and Paul Hancock. Both were savagely attacked in their own homes. Andrew Dawson called himself an ‘Angel of Mercy’ and he was convicted once again of murder and returned to his prison cell, this time with no chance of ever being released.
The Criminal Brain
There are many areas of the brain that have been pinpointed by neuroscientists as being involved in criminal behavior. These are the areas generally considered significant for regulating behavior such as impulsiveness, decision-making, and emotions.
The area of the brain researchers were interested in for this research is a small area in the frontal cortex of the brain called the anterior cingulate cortex (ACC). This area is involved in many day-to-day tasks and is one of the more active brain areas for most individuals.
The prisoners involved in the New Mexico prison study were monitored for 3 years following their release. In those 3 years, 53% committed a crime and were arrested, 44% committed a non-violent crime and 9% committed a violent crime.
The ACC has been linked with being more active in normal healthy individuals when they tried to restrain themselves from responding during a go/no-go task. It is an area of the brain which responds when an individual actively resists a behavior.
Researchers found that the New Mexico prisoners who showed less ACC activity during the quick decision tasks were also those who were more likely to be arrested again after release from prison. This suggests a difference in the ACC activity for individuals who are potentially more impulsive which raises their risk of reoffending in the future.
“. . . And that’s really why I wrote The Anatomy of Violence. I want more people to understand why people commit crime. I want them to know the brain mechanisms behind these acts, and what factors, including environmental influences, shape the brain processes that predispose to violence.” – Dr Adrian Raine
Another area of the brain that has received a lot of attention in brain imaging research when exploring criminal behavior is the amygdala. This is an area that lives in the temporal lobe of the brain and is part of our limbic system. Its functions involve our emotions, and particularly controlling automatic fear, anger and pleasure responses.
Studies have indicated a link between the size of the amygdala and people with psychopathic tendencies. Yang and Schug in 2009 conducted a study with 27 individuals who scored highly on the Psychopathy Check-List suggesting they fall into the category of a psychopath (which about 1% of the population does), and found 18% of them had a smaller amygdala when compared to 32 normal non-psychopathy controls.
This is further evidence that there may be physical differences which can be measured in the brain of individuals who could pose a higher risk of engaging in criminal behavior or the case of this study, fall into the psychopath group.
When focusing on functioning areas of the brain, what happens when such areas are damaged through injury has not escaped attention. We know from brain injury studies that frontal lobe injury especially can have an effect on an individual’s behavior and some have suggested this can contribute to violent and aggressive behavior.
We also know from such case studies that often other cognitive and mental functions can remain unaffected and intact after such injuries. The brain injury suffered by Phineas Gage after an extraordinary industrial accident in 1868 has provided psychology with a remarkable example of the effects of frontal lobe brain damage and the personality and behavior changes that can occur as a result.
Phineas Gage was a 25-year-old man working on a railroad bed in Vermont in September of 1848 when he suffered a horrific accident. While using a tamping iron to pack explosives into a newly created hole to clear surrounding rocks, the powder exploded and propelled the iron upwards with some velocity towards Gage himself.
The tamping iron, which was around 13lbs in weight, 1 meter long and 3 cm in diameter pierced through his lower cheek, passed through his brain and exited at the top of his head, falling to the ground some feet away. Amazingly, Phineas Gage survived his injuries but his personality transformed from a polite, friendly and reliable man to an unreliable individual who made bad judgments and seemed to have lost many of his social skills.
Psychology and Neurology Professor Hanna Damasio and her colleagues tried to recreate the damage that must have occurred to Gage’s brain using his skull and the original bar. She recreated the original shape of his brain prior to the accident using exact measurements and neuroimaging techniques.
Using Gage’s skull and the detailed accounts of the accident, Damasio was able to reconstruct the likely trajectory of the tamping iron and simulated those trajectories using modern computer programming. In this way, she was able to see exactly which brain regions were damaged due to the injury and therefore have a clear idea of which physical areas of the brain, when damaged, changed the behavior and personality of this individual and in what way.
This type of brain damage has been seen in other patients who experienced similar behavior changes to Gage, confirming the prediction that social and personal rational decision-making can be heavily disrupted through such brain injury alongside the processing of emotion.
Researchers who have studied war veterans who suffered brain injuries during the First and Second World Wars have found evidence of an association between aggressive or antisocial behavior and frontal lobe brain damage. Researchers Brower and Price From Harvard Medical School in Boston tested 279 veterans who had suffered head injuries and 57 normal control participants with no head injuries. Behavior, aggression and violent attitudes were examined using questionnaires, self-reports and family reports for all participants.
Veterans with frontal lobe head injuries consistently scored higher on the aggression/violence scale than control participants with no head injuries and other veterans with injuries in other parts of the brain. Their scores generally related more to verbal outbursts and tendencies rather than physical aggression and/or violence.
If such research can provide us with data on how criminal behavior may differ neurologically, it is possible this information could be used to try and address criminality in a different way. It is extremely difficult to predict any behavior from an individual with accuracy due to the sheer number of factors, both internally and externally, that could influence that behavior.
However, what these kinds of studies show is the potential for differences in brain structure and function to give an indication of a higher risk or more probability of criminal behavior. It should be noted that research to date is not entirely conclusive in terms of predicting an individual’s criminal behavior.
For example, the low activation in the ACC found by Aharoni et al (2013) in the New Mexico prison study could be influenced by other factors, such as error calculation, so it is difficult to say with any certainty how much lower ACC activity could contribute to criminal behavior.
Furthermore, the Vietnam Head Injury Study by Grafman et al (1996) did not collect data on the prior history of aggression, employment and socioeconomic status, any mental health disorders or substance misuse issues. Without this information, it is difficult to know exactly how much of these results can be reliably attributed to frontal lobe brain injury.
Although such research is still in its infancy, the emerging science of neurocriminology and the possibility of predicting criminal behavior is becoming a powerful one. With the ability to demonstrate differences between individual’s brains and particularly with criminal brains, comes a number of questions regarding self-control and whether an individual has impaired ability to regulate their criminal behavior.
This, of course, has some serious ramifications once inside a courtroom facing a serious criminal charge. Such scientific evidence has already started to make its way into the criminal justice system where an individual’s biology is being raised as a factor in their behavior. The future for scientific research and discoveries regarding the criminal brain is exciting; however how this will impact and be incorporated into the criminal justice system is much more complicated and unclear.
- Brower, M.C., and Price, B.H (2001) Neuropsychiatry of frontal lobe dysfunction in violent and criminal behavior: a critical review, J Neurol Neurosurg Psychiatry, 71, pp720-726
- Eyal Aharoni, Gina M. Vincent, Carla L. Harenski, Vince D. Calhoun, Walter Sinnott-Armstrong, Michael S. Gazzaniga, Kent A. Kiehl (2013) Neuroprediction of future rearrest. Proceedings of the National Academy of Sciences. 110 (15) pp6223-6228; DOI: 10.1073/pnas.1219302110
- Grafman, J., Schwab, K., Warden, D., Pridgen, A., Brown, H.R. and Salazar, A.M (1996) Frontal Lobe Injuries, Violence and Aggression: A report of the Vietnam Head Injury Study, Neurology, 46, pp1231-1238
Guy, F. (2016, Mar 2). Can Criminal Behavior Be Predicted Using Brain Scans?. Crime Traveller. Retrieved from https://www.crimetraveller.org/2016/03/brain-scans-criminal-behavior/