Scientists reveal why psychopaths commit violent crimes

Scientists reveal why psychopaths commit violent crimes

A new study has shed light on what drives psychopaths to commit violent crimes.

According to the research, psychopaths - who are often portrayed as cold and calculating - act in the way they do because their brains are wired to overvalue short-term rewards.

This same brain wiring may also lead them to avoid thinking about the consequences of their actions, Harvard researchers found.  

One expert compares the impulsive nature of the psychotic mind to that of a compulsive over-eater or drug addict.

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The brains of psychopaths are hardwired to be violent and dangerous, a new study has found. Pictured is anti-hero and notorious psychopath Francis Underwood from the US TV drama series House of Cards

INSIDE THE BRAIN OF A PSYCHOPATH

The team scanned the brains of 49 inmates at two medium-security prisons in Wisconsin over two hours.

The inmates took part in a type of delayed gratification test which asked them to choose between two options - receive a smaller amount of money immediately, or a larger amount at a later time.

The results were fit to a model that allowed re searchers to create a measure of how impulsive each participant's behaviour was, as well as identify brain regions key to assessing the value of such choices.

People who scored high for psychopathy showed greater activity in a region called the ventral striatum - known to be involved in evaluating reward - for the more immediate choice.

'So the more psychopathic a person is, the greater the magnitude of that striatal response,' Dr Buckholtz said.

'That suggests that the way they are calculating the value rewards is deregulated - they may over-represent the value of immediate reward.'

The researchers said they hope to erase the popular image of psychopaths as cold-blooded monsters and see them as humans whose brains are wired differently.

'They're not aliens , they're people who make bad decisions,' said study lead author Dr Josh Buckholtz, a psychologist at Harvard University.

'The same kind of short-sighted, impulsive decision-making that we see in psychopathic individuals has also been noted in compulsive over-eaters and substance abusers.'

The team claim that the choices that psychopaths make are more important to their actions than their stereotypical emotional detachment.

'For years, we have been focused on the idea that psychopaths are people who cannot generate emotion and that's why they do all these terrible things,' Dr Buckholtz said.

'Even though psychopaths are often portrayed as cold-blooded, almost alien predators, we [the researchers] have been showing that their emotional deficits may not actually be the primary driver of these bad choices.'

The team scann ed the brains of 49 inmates at two medium-security prisons in Wisconsin over two hours.

The inmates took part in a type of delayed gratification test which asked them to choose between two options - receive a smaller amount of money immediately, or a larger amount at a later time.

The results of those tests were then fit to a model that allowed researchers to create a measure of not only how impulsive each participant's behaviour was, but to identify brain regions that play a role in assessing the relative value of such choices.

What they found, Dr Buckholtz said, was people who scored high for psychopathy showed greater activity in a region called the ventral striatum - known to be involved in evaluating reward - for the more immediate choice.

'So the more psychopathic a person is, the greater the magnitude of that striatal response,' Dr Buckholtz sai d.

Say word ‘psychopath’ and most people think of a character like Hannibal Lecter from the 1991 film The Silence of the Lambs. A study has found that psychopaths impulsively over-value immediate rewards and neglect the consequences of dangerous or immoral actions

'That suggests that the way they are calculating the value rewards is deregulated - they may over-represent the value of immediate reward.'

When Dr Buckholtz and colleagues began mapping which brain regions are connected to the ventral striatum, it became clear why.

'We mapped the connections between the ventral striatum and other regions known to be involved in decision-making, specifically regions of the prefrontal cortex known to regulate striatal response,' he said.

'When we did that, we found that connections between the striatum and the ventral med ial prefrontal cortex were much weaker in people with psychopathy.'

That lack of connection is important, Dr Buckholtz said, because this portion of the prefrontal cortex role is thought to be important for 'mental time-travel' - envisioning the future consequences of actions.

'The striatum assigns values to different actions without much temporal context' he said.

'We need the prefrontal cortex to make prospective judgements how an action will affect us in the future - if I do this, then this bad thing will happen.

'The way we think of it is if you break that connection in anyone, they're going to start making bad choices because they won't have the information that would otherwise guide their decision-making to more adaptive ends.'

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