Does prison work?

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Origins of Violence

Brain Function: The Amygdala and the Frontal Lobe

Numerous studies have shown that there are correlations found between brain function and violent behaviour. In order to fully understand these studies, it’s important to have a general understanding of some of the functions of these parts of the brain.

One important function of the frontal lobe is to regulate our impulsive decision making. It also lets us make long-term decision making in the sense that it allows us to foresee and imagine possible implications for our actions. It sort of acts like a “break” on our impulsive behaviour. So when you get really angry at your teacher and you want to curse but don’t because you know that it will get you in trouble, you have your frontal lobe to thank. The impulsivity of young children can be explained through their still-developing frontal lobes.

So based on this, would you think that people who act violently have normal functioning, high functioning or low functioning frontal lobes?

Studies have shown that there is a correlation between low functioning frontal lobes and violent behaviour. One study compared 279 Vietnam war veterans who had suffered head injuries that resulted in damage to areas of the brain with 57 healthy controls. The researchers hypothesized that the prefrontal cortex helps exert control over primitive reactions to environmental provocation. In other words, when something makes us emotional our prefrontal cortex helps to stop us from reacting in a violent or aggressive manner.  Family observations and self-report forms were used to gather data on violent and aggressive tendencies in the participants. The researchers gathered data on a range of aggressive and violent attitudes and behaviours. The results showed that those veterans who had damage to their prefrontal cortex had higher levels of violence and aggression than the controls or veterans with damage to other parts of the brain. Verbal violence and aggression, as opposed to physical, was more commonly reported. The study found no correlation between the extent of the brain damage and behaviour, but instead found that “disruption to family activities” was more likely to cause aggressive and violent behaviours. (Graftman et al, 1996). In this study we can see that while the evidence suggests there are biological correlates of violence and aggression, there is still an environmental factor that is influential.

Genetics: The role of the warrior gene

The MAOA gene, nicknamed the “warrior gene” because of its connections with aggression, has been a favourite in the media. Human behaviour is never as simple as isolating a single gene and saying it’s responsible for behaviour. For instance, males with low activity in their MAOA gene (MAOA-L) show great activity in their amydala and less activity in their prefrontal cortex during emotional arousal (Raine, 2008; Meyer-Lindenberg, 2006).


Only three mass shooters in the United States in the past fifty years have been females. Why is this? Could it be because of the way boys are raised, or are they just biologically engineered towards violence?

The role of testosterone has been extensively studied in the context of explaining aggression (and thus is highly relevant to studies of violent crime). Testosterone is produced in the testes in males and to a lesser extent in the ovaries of females. It is an important sex hormone and plays a significant role in the development of young males. Males have higher levels of testosterone than females, naturally.

Experiments of rats has shown evidence of the relationship between testosterone and aggression. When rats are castrated (testes removed) they became more passive and less aggressive. However, when they are given injections of testosterone their aggressive tendencies return. This suggests a strong causal link between levels of testosterone and aggressive behaviours.

But can the same be said for humans? Environment can also affect hormone levels in humans. Testosterone has not only been linked to aggressive behaviours, but also to social dominance. That is to say, wanting to be at the “top” of the hierarchy, the “alpha”. Testosterone levels have been correlated to social dominant behaviours. Moreover, it has also been shown that testosterone levels rise in competitive situations (e.g. chess tournaments, tennis matches and stock broking). One study compared testosterone levels in college aged US males after being bumped in a corridor and being insulted. This study compared students from the Southern States of the USA (Virgnia, Alabama, etc) and those in Northern Sates (New York, Massachusetts, etc.). A “culture of honour” is common in the southern states, which means there’s a common belief that men are supposed to defend their honour. This is not the same in the northern states. The students from the southern states who were bumped and insulted showed a higher increase in testosterone levels as a result than did those from the Northern States.

Reducing Violence

How does prison work? Or does it?

What’s important to remember is that the term violence covers a range of activities, from verbal abuse to serial killing to tax evasion. We are going to focus on violent crime. The first strategy designed to reduce crime we will examine is the traditional prison system. By “traditional” I mean the sort of environment you imagine when you think of the word “prison” or “jail”. Prison aims at reducing crime primarily in three ways:

  1. Prevention
  2. Deterrence
  3. Rehabilitation

Prevention: Prison is designed to remove dangerous criminals from society to keep the rest of society safe and to prevent them from committing further acts. This is pretty straightforward: if a murderer is in jail they can’t keep reoffending (except for violence in the prison itself, which we’ll get to later).

Deterrence: Prison also serves as a source of fear so people will modify their actions to avoid being arrested and put in prison. For instance, would you be more likely to complete your homework if there was no-one going to check it, or if someone was checking it and if it wasn’t done you’d get a detention? This is the deterrence factor in prisons – it is hoped that the idea of going to prison will help put a break on criminal behaviour because it’s an unpleasant place and people won’t want to go there.

Rehabilitation: a third and perhaps the most important way in which prison aims to reduce recidivism (reoffending) is through rehabilitating criminals. That is to say, the criminals will leave the prison “better” people and will be less likely to commit the crime again because their behaviour has been modified. Perhaps they will be less likely to commit the crime because of the terrible time they’ve had in prison and they will not want to go back there, or because they have undergone other therapy, treatments or experiences that aimed to adjust their thoughts and behaviour.

            Does prison “work”?

This is a difficult question to address definitively and it varies from one country to the next. It’s impossible to know the extent to which prison works as a deterrent because the people who have been deterred never commit the crime, so there are no statistics on this. However, what we can do is examine the origins of violent crime and hypothesize the extent to which committing different types of crimes may be more or less likely to be affected by the deterrence factor.

Similarly, it’s impossible to know the extent to which crime is reduced through incarceration because people in jail don’t commit more crimes during their time in jail.

Perhaps the most important aspect of prison to examine is the idea of rehabilitation and recidivism. Rehabilitation means to address the underlying issues within the individual and to make these better so they won’t commit more crimes when they are released (which is called recidivism).

Using psychological research into the origins of criminal behaviour, environmental influences on behaviour, neuroplasticity and psychological treatments, we can make predictions as to the extent to which the traditional prison system will rehabilitate or exacerbate etiologies of criminal behaviour.

The following graph from Wikipedia gives just one insight into recidivism in the US.



A Description of a Traditional Prison

It’s difficult to give a precise description of a prison because there is so much variance across countries, and even between prisons (e.g. between maximum security and minimum security; male to female). The following descriptions are generic and aimed to give a basic idea of what a typical prison may be like. However, this is highly contextual. Prisons in some Scandinavian countries, for instance, operate on completely different principles to those in the United States
The most important aspect of a prison is a lack of freedom. Prisoners are put in cells by themselves, or sometimes with one other cell mate. Remember that it’s the tax payers’ dollars that are spent keeping prisons running and most people who pay their taxes don’t want to see a lot of it going on prisoners; they’d rather see the money spent on health, education and other public services. So in terms of diet, the food in prisons isn’t usually great. There also isn’t a lot investment put into resources available to prisoners. There’s typically an outside area for “recreation” including basketball courts, softball fields, weight training facilities, etc. The cells are usually pretty bare as there is a fear that any wires, metals, ropes or almost any object can be made into something that can do harm to another prisoner or to the inmate themselves.




Evaluating the “Traditional” Prison System and Alternatives

Alternatives to the traditional system are those that are similar to those in Norway. Here the ethos surrounding prisoners is not about justice or punishment, but the focus is on rehabilitation and allowing prisoners the time, resources and fair treatment to become better people.

When evaluating the effectiveness of different prison types, like with any discussion in psychology, it’s essential that we have psychological evidence in the form of research to support explanations, conclusions and hypotheses.

Relevant Research

Environment and Brain Development

Research has shown that our brains can change due to environment and experience. So if research shows that there are biological correlates of criminal behaviour then surely prison should be designed to address those correlates.

The key biological correlates I’m referring to are as follows:

  • Abnormal function (hyperactivity) in the amygdala
  • Lower activity and less development in the prefrontal cortex
  • High levels of testosterone
  • Low levels of serotonin

Rosenzweig’s experiments on rats in various cages (enriched, deprived and control) was some of the earliest research into the role that our environment can play on brain development. From these initial animal studies it was concluded that brain development is not just influenced by genetics, it is also affected by the level of stimulation we have in our environment. The concept of neuroplasticity has become almost irrefutable in modern psychological research: our brains have the ability to change and adapt over time. If research suggests that there are biological correlates of criminal behaviour related to brain structure (front lobe activity, amygdala, neurotransmitter levels, etc.) and we know our environment can change these biological structures then this has important implications in how we treat criminals.

Maguire’s research into comparisons of environmental stimuli and cognitive practice effects on London bus and taxi drivers also showed that not only does our environment affect our brain development, but also our cognition can as well. The fact that the taxi drivers had to remember far more streets than the bus drivers actually resulted in difference in structures between the two brains. These structural changes also affected the acquisition of new memories (with the bus drivers being better at this than the taxi drivers). This research simply further supports the idea of neuroplasticity and the fact that brains can change with experience.

Another researcher who has spent years studying the ways cognition can affect brain activity and structure is Richard Davidson. Davidson has compared the brains of monks who have spent their lives meditating (over 50,000 hours some of them) with control groups who have little to no experience in meditation. The findings are that the brain structures and activity of various parts of the brain are different than the controls. Again, the conclusions show that consistent cognitive activity, not only environmental stimuli, can affect our brain activity.

Stress can be a result of environmental factors and cognition. Studies have shown that stress disrupts the functioning of the prefrontal cortex (PFC). The effects can be after short-term exposure to stress and more long-term. Research shows that even quite mild stress can reduce cognitive functions of the PFC.

More prolonged stress has been shown to actually change the structure of the PFC. People who have been diagnosed with PTSD tend to have reduced function in their PFC and hypersensitive amygdala. If the PFC is known to modify our impulsive actions it shouldn’t be too hard to see the relevance of environment effects on this part of the brain in terms of rehabilitation of violent criminals.

It’s important not to neglect the social factors that are involved in prisons as well. Zimbardo’s Stanford Prison Experiment showed the effects of a prison environment on guards as well as on the prisoners. One important conclusion drawn from this study is that humans may modify their behaviour based on the situation. Moreover, they may behave in a way that is expected of them. Thus, it stands to reason that depending on the philosophies and the nature of the prison the behaviour of the guards could be drastically different – which would have various results for the inmates.


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