On December 14, 2012, Adam Lanza, who was only 20, shot his mother then shot twenty children and six adult staff members in a mass killing at Sandy Hook Elementary School in Newtown, Connecticut. This mass murder is on record in American history for the as being the second most deadliest mass shooting by a single person , and the second deadliest mass murder in a elementary school. Although this incident is the most fatal public school shooting in the United States. So, what causes people to kill?Due to irrational emotions and psychological imbalances in the Anterior Rostral Prefrontal Cortex of the brain which is important for processing emotions, fear and social and motor skills, people commit violent crimes that hurt others (Kate Kelland).Adam Lanza was diagnosed with, “sensory integration disorder”, also now known as sensory processing. People who have sensory processing disorder or SPD may over-respond to stimuli and find clothing, physical contact, light, sound, or food unbearable. They may also under-respond and feel little or no reaction to pain or extreme hot and cold.The emotions that violent criminals have can be categorized into specific groups that can be considered motivations for them to commit such crimes.Everyday Psychology has made a Typology of Violent Offenders who do not suffer from brain defects and reasons why they would commit homicide. The first group is the Chronically Aggressive Individuals. These are people who get easily frustrated, and have limited or poor impulse control. These people frequently express anger or hostility (through passive-aggressive behavior) and resent authority. They usually believe violence and/or aggression are lawful responses to various interpersonal problems in life. They find pleasure or reinforcement is derived from the expression of anger.Often they display the characteristics of a “stimulus seeker” – they participate in bold, fearless, or reckless behavior and are more likely to exhibit substance abuse. Typically, violence occurs in a situational context: an offense, fight, or disagreement but are less likely to engage in acts of unexpected “explosive” violence (Paul G. Mattiuzzi). These types of people do not like to be caught off guard because they like to be in control. The second group is The Over-Controlled Hostility Type. These people seem to be polite, serious, sober, and rarely display or express anger.They do not cuss or yell, and may even be offended by such behavior. They are likely to be morally righteous and see themselves as “good people”, and often see others as “not such good people”. After the violence, people say that they never expected it, “He always seemed like such a nice guy; he was always so quiet” (Paul G. Mattiuzzi). These types of offenders can be very unpredictable and unexpected. The third group is The Hurt and Resentful. They feel that people walk on them and that they are never treated fairly.When they are passed over, the blame is always placed on someone else. They think things are easier for everyone else; other people get more and have more advantages. They do not accept criticism well and in response to reprimands; they develop grudges, which are sometimes deeply held. This is when the Violence occurs because they hold grudges and are “impotent” to deal with their anger in other ways (Paul G. Mattiuzzi). These individuals exhibit self sympathy and often feel badly for themselves. The fourth group is The Traumatized.Whose aggression occurs in response to a single, massive assault on their individuality. Usually something happens that is potently offensive, absolutely intolerable, and which strips them of all sense of personal power (Paul G. Mattiuzzi). Usually they have a hard time coping and moving on so they display aggressive behavior. The fifth group is The Obsessive. They are immature and egotistical individuals who demand or crave attention and affection, and get upset when deprived of desired gratifications (Paul G. Mattiuzzi). The sixth group is The Paranoid.They typically engage in behaviors which make their paranoid beliefs come true. Many times delusions may reach the point at which the person is out of contact with reality (Paul G. Mattiuzzi). People who experience this place blame on anyone else because they are in a false sense of reality. The seventh group is The Insane. Usually rare, but does not understand the nature and quality of their actions. Typically they have essential misperceptions of reality, are incapable of rational behavior, and delusional beliefs prevent them from knowing between right and wrong behavior.Their beliefs and perceptions are different than those of reality. They confuse beliefs about what is right, what is wrong, and what is necessary (Paul G. Mattiuzzi). They have an altered state of mind that causes them to display violent behaviors. The eight and last group is The Just Plain Bad & Angry. This is a combination of the seven previous groups with the exception of the Insane group. Usually they display the characteristics of being: angry, hostile, jealous, resentful, impotent, and disturbed individuals.They feel socially isolated, socially inadequate, and worthless (Paul G. Mattiuzzi). Abnormalities within the Anterior Rostral Prefrontal cortex and Temporal Poles have been studied to see that the lack of grey matter that triggers empathy can cause some people to commit violent crimes. A psychopath is a person with a psychopathic personality, which is apparent as amoral and antisocial behavior (such as Adam Lanza). Usually they display a lack of ability to love or establish meaningful personal relationships, extreme self-interest, and failure to learn from experience.People who suffer from this, compared to violent offenders that are healthy, have structural differences in their brain that cause them to have less grey matter in certain areas. These areas of the brain are important for processing others people’s emotions, intentions, fear and social skills (Kate Kelland) so, when people are lacking in these areas they become dangerous. There are two divisions that separate people who commit homicide; psychopaths who are lacking normalities of the brain, and sociopaths who are individuals with irrational emotions.The Diagnostic and Statistical Manual of Mental Disorders (DSM) lists both Psychopathy and Sociopathy under the heading of Antisocial Personalities because they both engage in similar actions and have similar characteristics. People commonly group sociopaths and psychopaths as the same thing. The differences between sociopaths and psychopaths are primarily differentiated by the origin of the disorder. In the mental health field the general opinion is that psychopaths are actually much more of an inborn occurrence while sociopath, which displays clinical presentation, is the consequence of environmental stressors.There are three general categories of therapy, behavioral therapy, cognitive therapy, and psychotherapy. Different therapy options have their advantages and disadvantages in treating Antisocial Personalities for both people who suffer from sociopathy or psychopathy, and a patient might tolerate one clinical setting or approach over another . There is no cure for sociopathy or psychopathy, but it can be managed well or it can be managed inadequately. For example, Sociopaths don’t respond very well to punishment, but they do respond to incentives.For psychopaths Diffusion tensor imaging (DTI) has become one of the most popular MRI techniques in brain research by allowing visualization and characterization of white and grey matter in the brain. ” DTI provides a capable way for comprehensive, noninvasive, functional anatomy mapping of the human brain (Assaf Y, Pasternak O)”. People that commit violent crimes have different motivations for different crimes, and most types of homicides can be characterized by the individuals that commit them (Paul G. Mattiuzzi). Antisocial Personality Disorders (ASPD) exhibit behavior that manipulates, exploits, violates the rights of others.Many people in the world experience Antisocial Personality disorders, and while not all people who suffer from them commit homicide they are very capable of it because they are usually impulsive, irresponsible, and lack remorse or feeling towards others (Anne- Marin B). Psychopaths do not have Antisocial Personality Disorders, they have parts of the brain that are not fully functioning properly, causing for them to not be able to understand other people’s emotions or process empathy the same as a “healthy” person. Sociopaths can have Antisocial Personality Disorders.There is not one general group that categorizes all sociopaths because they can experience many different emotions that place them in different groups. Either way people who have these disorders display irrational behavior that can come in the forms of violent abuse. There is no cure for an Antisocial Personality Disorder but there are ways to manage and control a person’s behavior so that they do not commit violent crimes. The most accurate way to do so is by knowing how they respond negatively to certain commands and trying to avoid triggering any of them so they don’t become troubled or feel the need to be aggressive.