Crime Library: Criminal Minds and Methods

'Movies Made Me Murder'

Violence and the Brain

Logo: Scientific American Mind
Logo: Scientific American Mind

In the December 2006 issue of Scientific American Mind, Daniel Strueber, Monica Luek and Gerhard Roth cover the latest work from brain researchers devoted to the subject of violence and aggression.  They focus largely on psychopaths who feel no empathy for their victims or regret afterward for what they have done.  They plan and kill in a disconnected manner. It turns out that "violence never erupts from a single cause," but instead derives from a combination of risk factors.

Book Cover: The Biology of Violence
Book Cover: The Biology of Violence

Debra Niehof, a neuroscientist, had already noted this with her book, The Biology of Violence, published in 1999, after she had studied twenty years' worth of research.  Specifically, she wanted to know whether violence was the result of genes or largely influenced by the environment.  In her opinion, both biological and environmental factors are involved, and each modifies the other such that processing a situation toward a violent resolution is unique to each individual.  In other words, a particular type of stimulation in a film is not going to provoke violence in every viewer.  One person might react, while another might be completely unaffected by the very same exposure.

The way it works, says Niehoff, is that the brain keeps track of our experiences through chemical codes. When we have an interaction with a new person, we approach it with a neurochemical profile, which is influenced by attitudes that we've developed about whether or not the world is safe, whether people are trustworthy, and whether we can trust our instincts. However we feel about these things sets off certain emotional reactions and the chemistry of those feelings is translated into our responses. "Then that person reacts to us," says Niehoff, "and our emotional response to their reaction also changes brain chemistry a little bit. So after every interaction, we update our neurochemical profile of the world."

For causal associations, Strueber and his associates focus on the negative experiences a person might have.  The risk factors included inherited tendencies, a traumatic childhood, and other types of negative exposures, all of which aggravate one another via interaction.  Being male is one risk factor, as is having a violent role model and showing frontal cortex abnormalities that promote impulsivity.  High-risk individuals might also develop a low frustration tolerance level and fail to learn social rules.  In males, a higher testosterone level has been linked to aggression.  (One study found this to be true of violent women as well.)  In addition, head injuries of certain types seem to predispose certain people to violence.

Dr. Adrian Raine
Dr. Adrian Raine

Among the more interesting studies — albeit with low numbers and with only adult male subjects — Dr. Adrian Raine and his colleagues at the University of Southern California, compared 23 psychopaths who'd been caught vs. 13 psychopaths who remained at large.  On the assumption that those who remained free were better planners, MRIs indicated that the "successful psychopaths" had a higher volume of gray matter in the frontal cortex than those who'd been caught.  In addition, the unsuccessful psychopaths showed an asymmetrical hippocampus.  Other researchers pinpoint dysfunctions of the amygdala as playing a part in a person's capacity to feel empathy (or not).  The balance of neurochemistry, too, has a role, which will be affected by a combination of one's heredity and one's environment.

It's safe to say that in cultures that tolerate violent images and even encourage them, there will likely be a greater propensity among young people and the mentally disturbed to be influenced toward acting out what they see.  If their options for dealing with conflict are limited to violence as a resolution, they will generally turn to violence themselves.  Some researchers have estimated that by the time a child reaches the age of eighteen, he or she has seen around 100,000 violent images on television, in film or in videogames.  It seems absurd to believe that such exposure will have little to no effect.

Book cover: The Copycat Effect
Book cover: The Copycat Effect

In The Copycat Effect, Loren Coleman indicates that any type of visual media that sensationalizes a crime can generate fallout in the form of mimicry.  Similar incidents generally follow within a few weeks.  We'll get to the mimicry angle later.  For now let's return to these cases.

 

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