|The brain governs self-control and the human conscience.
Image source: http://thefuturon.com
Self-control and moral judgment are major determinants of criminal behaviour. Crimes are primarily the result of inadequate self-restraint and poor moral discretion. Self-control is the ability to control one’s own behaviour, while moral judgment is the ability to distinguish between right and wrong. It is believed that every human being experiences some form of tendency towards socially deviant behaviour from time to time. If that is true, then it is not one's immoral urges that make them a criminal; it is instead the succumbing to those compulsions by committing crimes that separates the criminals from those who are not. On the other hand, there are those who do not understand that the crimes they commit are wrong. Individuals without a good sense of morality, along with those with weak self-control, are likely to be more susceptible to committing crimes than the norm. Like the many other aspects of the human psyche, self-control and moral judgment are governed by the brain. Understanding the neurobiological aspect of human self-control and moral judgment is pivotal for the prevention of criminal activity and treatment of criminal tendencies.
Table of Contents
1.1 Prefrontal cortex
The prefrontal cortex is located at the anterior portion of the frontal lobe. It is commonly associated with planning, motivation, emotion, social interactions, reward and punishment and ultimately, decision making. Functional neuroimaging, brain lesion studies, and animal models have implicated the ventral medial prefrontal cortex and orbitofrontal cortex in particular to be heavily involved in self-control and moral judgment. In contrast, logic and reason have been associated with activity in the dorsolateral prefrontal cortex (dlPFC). Damage in the prefrontal cortex has often been associated with psychopathic behaviour, which includes impulsive aggression and the lack of empathy. Indeed, patients with frontotemporal dementia are often reported to exhibit socially and morally deviant behaviour. These abnormal, psychopath-like traits that patients with prefrontal cortex deficits tend to manifest has been referred to as acquired psychopathy or "pseudopsychopathy".
1.1a Orbitofrontal cortex
Research has shown that the orbitofrontal cortex (OFC) is of great importance for regulating self-control as it normally functions to inhibit socially inappropriate behaviour, such as aggression. The OFC has also been implicated to be important for proper response and sensitivity to rewards and punishments. Much of what is currently understood regarding the role of the OFC comes from human brain lesion studies. Generally, patients with OFC lesions tend to perform more impulsively in self-report, cognitive and behavioural tests than non-OFC lesion patients and normal individuals. A common task in these tests is to choose between two options the one that reaps the greatest monetary reward. The first option may give frequent large rewards with rare small losses, while the other option may yield infrequent small rewards but common large losses. For example, option A may give a reward ranging from $80-$250 70% of the time with losses of $10-$60 30% of the time. On the other hand, option B may give a substantially lower reward of $30-$65 40% of the time but a huge loss of $250-$600 60% of the time. Some time during the task, the two options are reversed and the time needed for participants to react accordingly is measured. Patients with OFC lesions in these studies typically cannot make the appropriate response to switch options when they are reaping greater losses than rewards. It is thought that the reduced sensitivity to rewards and punishments found in OFC patients is the cause of poor self-control and impulsivity. In the context of the criminal mind, criminals may have poor self-restraint because of hypoactivity and dysfunctionality of the OFC. Typically, these criminals would be more inclined towards immediate pleasures rather than future rewards, as well as having neglect for future consequences.
1.1b Ventromedial prefrontal cortex
The ventromedial prefrontal cortex (vmPFC or VMPC) is believed to play a significant role in decision making, especially regarding social and moral issues. Like the OFC, brain lesion studies are one of the most common models used to investigate the function of the vmPFC in humans. The majority of evidence from these studies suggest that patients with vmPFC lesions exhibit an abnormally utilitarian or extremely rational pattern of decisions for certain moral dilemmas. An example of a utilitarian response to a moral dilemma would be the choice to sacrifice two people to save the lives of seven others. It is important to note that the moral judgments made by vmPFC patients differ from non-vmPFC patients and normal individuals only for dilemmas that involve personal interaction; impersonal moral problems tend to give consistent responses throughout all groups of participants.
The trolley problem is a common impersonal dilemma where one must decide whether or not to pull a certain lever. Pulling the lever will redirect an out-of-control train from one path that will take the lives of five people to another track that will take the life of only one. An example of a personal moral dilemma is the classic footbridge dilemma. In this scenario, a speeding train will soon claim the lives of five workers on the railroad track. The person given this dilemma is alongside a rather large individual with both of them atop a bridge above the train track and in between the train and the workers in danger. The person is then given the option to push the large individual off the bridge and onto path of the oncoming train to prevent the deaths of the five workers, thereby sacrificing the life of one to save five others. For the trolley and footbridge problems, it is considered morally acceptable by the norm to pull the lever to save five at the cost of one, but immoral to push the large person off the bridge for the sake of the five workers. When faced with impersonal moral dilemmas, patients with vmPFC lesions produce responses similar to those of the control participants. However, for personal moral dilemmas, vmPFC patients chose the most utilitarian option more often and quicker than the control groups.
In one study, emotional processing in participants was detected and measured using skin conductance response (SCR) recordings. Unlike participants in the control group, vmPFC patients did not elicit SCRs prior to choosing to sacrifice one for the sake of many in personal moral dilemmas. Therefore, normal participants are generally less likely to make the utilitarian judgment when faced with personal moral dilemmas because they must first overcome an aversive emotional response to do so, while vmPFC patients do not. Another study showed that vmPFC patients rely on expected outcomes rather than emotional responses to make decisions. For instance, in the study, vmPFC patients considered failed, attempted murder as more acceptable than death by accidental poisoning. Unlike the control group, vmPFC patients wrongly judged the accidental poisoning of someone to be more immoral than a failed poisoning attempt, even though harmful and murderous intent was obvious in the latter but not in the former scenario. In regards to the criminal mind, some offenders may commit crimes without acknowledging that they have done anything wrong, and the poor discretion seen in these criminals for moral judgments may be a result of deficits in the vmPFC.
1.2 Limbic system
Several studies have implicated the subthalamic nucleus of the basal ganglia, as well as the hippocampus to be involved in making moral judgments. Functional neuroimaging and rat models have also provided evidence for the involvement of the nucleus accumbens with impulsive decision-making. However, the amygdala is the structure in the limbic system that is most commonly believed to play the major role in the context of self-control and morality. Earlier studies have shown the involvement of amygdala degeneration in impulsive aggression. However, a recent study found that the total amygdala volume has no apparent correlation with either impulsivity or aggression. Instead, it was shown that the left and right ventral amygdala were both associated with impulsivity, while only the left dorsal amygdala was associated with violent behaviour. Among other emotions, the amygdala plays a significant role for the processing of emotions involved with morality. For psychopaths, studies have revealed less activity in the amygdala when making moral judgments than normal individuals. The amygdala is also known to be intricately interconnected with the vmPFC and the OFC, which are both crucial for self-control and moral judgments. Most psychopaths have aberrant amygdala-vmPFC connections. which may account in part for poor decision-making regarding moral dilemmas. There is also evidence that suggests that aberrant amygdala-OFC connections lead to impulsive aggression.
1.2b Subgenual cingulate cortex
Evidence from fMRI studies have implicated the involvement of the subgenual cingulate cortex (SCC) in the emotional processing of guilt. Greater activity in the SCC has been correlated with stronger feelings of guilt, especially in the context of causing harm to another. SCC activity does not however, seem to be related to compassion. The involvement of the SCC in moral judgment was investigated further in a recent study that revealed a positive correlation between reduced SCC activity and greater tendency towards utilitarian judgments. Individuals with hypoactive SCCs do not have to overcome any feelings of guilt after making what would normally be a emotionally aversive decisions. With little or no feeling of guilt to hold them back, it is likely that individuals with SCC deficits are more prone to commit crimes than normal individuals.
Neural activity in the brain relies heavily on neurotransmitters. Activity in the regions of the human brain that govern self-control and moral judgment is no exception to this. A few neurotransmitters that have been implicated to be involved in impulsivity and morality are GABA, dopamine, and serotonin. Using magnetic resonance spectroscopy, one study showed that higher concentrations of GABA in the dorsolateral prefrontal cortex correlated with rash behaviour in male participants. The role of dopamine in relation to impulsivity is much more poorly understood. The collection of contradicting evidence regarding this topic attests to that. For instance, one study showed that approximately 10% of Parkinson's disease patients began to exhibit compulsive gambling, shopping, enhanced sex drive, and overeating following dopamine replacement therapy. On the contrary, another study found reduced dopamine transmission in adults with ADHD, a disorder commonly affiliated with impulsiveness. Evidence from research investigating the role of serotonin in self-control has been relatively more consistent. Several studies of suicide attempters have found that reduced serotonin levels are associated with greater impulsiveness. Serotonin also seems to play an important factor for the moral aspect of decision-making, as one study showed that participants with elevated serotonin levels were reluctant to make utilitarian decisions that involved causing harm to another. It is implied that serotonin amplifies aversive emotions, especially those prevalent in moral judgments. The therapeutic use of Citalopram, the drug used in this study, as a possible treatment for poor moral judgment has been discussed. Citalopram, which functions to inhibit the reuptake of serotonin, caused more frequent rejection of decisions that lead to harmful outcomes in moral dilemmas. However, the effects of citolopram were weaker in individuals with low empathic concern and higher in those with high empathic concern. Therefore, the drug unfortunately may not have much of an effect on individuals with little or no empathy or sense of morality.
Several genes have been linked to impulsive aggression and poor moral discretion. Serotonin-related genes such as the SLC6A4 gene that codes for the serotonin transporter, and the HTR2B gene that codes for serotonin receptor 2B have been implicated in human impulsivity. The MAOA gene located on the X chromosome codes for the enzyme, monoamine oxidase A, which degrades various neurotransmitters including serotonin and dopamine. Studies have shown that the MAOA-H allele yields a more active enzyme than the MAOA-L enzyme. Individuals with the MAOA-L allele have been shown to be more prone to impulsive aggression than those with the MAOA-H allele. Regarding moral judgment, a recent study claiming to be the first to reveal a link between genetics and human morality, found that carriers of the C allele for the oxytocin receptor gene (OXTR) wrongly judged accidental harms to be more immoral than failed attempted harms. The C allele is believed to confer higher expression of the oxytocin receptor than the TT allele. It is suggested that individuals with higher levels of oxytocin rely more on the emotions that result from the negative consequences of accidental harms to make their decisions than those with lower levels of oxytocin.
4. Other factors
4.1 Substance abuse
There are many other factors that may cause impulsive and immoral behaviour, with some having a greater influence than others. A common factor that is widely known to cause erratic behaviour and is often linked with criminal activity is substance abuse. Studies have shown that marijuana use heightens impulsivity and there is also evidence that shows that habitual marijuana users suffer from white matter degeneration in the frontal lobe, which includes the prefrontal cortex. Another substance notorious for impairing judgment and disinhibiting inappropriate behaviour is alcohol. A recent study showed that excessive alcohol consumption may not only give short-term effects but also cause long-term deficits for moral judgments. It was shown that patients with alcohol dependence (AD) made more utilitarian decisions for personal moral dilemmas than the norm. It is suggested that over time, frequent alcohol consumption may cause vmPFC degeneration. Another recent study on AD patients found a positive correlation between impulsivity and the severity of the substance use disorder. Therefore, brain damage due to long-term heavy drinking may extend to the orbitofrontal cortex as well as other brain regions.
4.2 Childhood abuse
The development of every human being is determined by the combination of genetics and the environment. Just as certain genes may confer susceptibility to impulsive or immoral behaviour, so may the environmental factors present in childhood do the same. Studies have shown that a significant portion of incarcerated felons have reported victims of bullying, physical abuse and sexual abuse. Experiences of child abuse have been reported in psychopaths and serial killers in particular. The study that investigated the association between the MAOA gene and impulsivity also found that the susceptibility towards impulsive aggression for carriers of the MAOA-L allele was further amplified for those who have experienced childhood abuse. Furthermore, the study that investigated the long-term effects of alcohol dependence on self-control also found greater impulsivity for the patients who were physically or sexually abused as children.
5. EMDR treatment for violent impulses
Eye movement desensitization and reprocessing (EMDR) is an eight-phase psychotherapeutic treatment designed to treat patients with posttraumatic stress disorder (PTSD). The goal of EMDR treatment is to address the unsettling experiences that haunt an individual. Developing more favourable responses to such experiences is done by replacing the negative cognitions (NC) associated with them with positive cognitions (PC). In a recent case study, EMDR was used to successfully alleviate the violent impulses of a military sergeant with PTSD. The patient had been serving in the U.S. Marine Corps for over ten years and during his second operation in Afghanistan, he began to envision disturbingly vicious images. The aggressive compulsions he experienced includes the vision of himself murdering his fiancée as well as shooting a fellow motorist on the road. As time progressed, the violent impulses he experienced grew stronger and more frequent. Throughout the 6-week treatment, emergence of the disturbing images was reduced to a significant degree and maintained at minimal level even after treatment. Although the efficacy of EMDR for the treatment of violent impulses in the general population is currently unknown, it should not be discarded as a possible remedy for impulsive aggression. After all, there is a prevalence of childhood abuse in criminal populations, and the trauma affiliated with such abuse may account for their compulsion towards socially and morally deviant behaviour. Therefore, EMDR, as well as other therapies for PTSD, such as exposure-based therapies (ET), cognitive-based therapies (CT), trauma-focused cognitive-behavioural therapy (CBT) and stress inoculation training (SIT) should be investigated for the promotion of prosocial behaviour.