Don't blame Hannibal Lecter, he cannot help being a callous murdering monster.

Psychopaths lack basic hardwiring in the brain that enables most people to be compassionate and caring, new research has shown.

American scientists studied 80 male prisoners aged 18 to 50 who were assessed for psychopathic traits.

Around 20% to 30% of the US prison population are believed to be affected by psychopathy compared with 1% of the general population.

Study Suggests 'Psychopaths' Have Impaired Sense Of Smell

Participants underwent brain scans while being shown videos of people being intentionally hurt and others of faces reacting to pain.

The results of the functional magnetic resonance imaging (fMRI) scans showed distinct differences in the brain responses of highly psychopathic and non-psychopathic individuals.

Psychopaths displayed significantly less activity in the ventromedial prefrontal cortex, lateral orbitofrontal cortex, amygdala and periaqueductal grey parts of the brain. Conversely, more activity was seen in the striatum and insula regions.

"A marked lack of empathy is a hallmark characteristic of individuals with psychopathy," said lead researcher Professor Jean Decety, from the University of Chicago. "This is the first time that neural processes associated with empathic processing have been directly examined in individuals with psychopathy, especially in response to the perception of other people in pain or distress."

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The findings are published online today in the journal JAMA Psychiatry. They may help explain why criminal psychopaths such as Lecter, portrayed chillingly on screen by Sir Anthony Hopkins, appear so lacking in remorse or compassion.

Psychopaths are known to be responsible for a disproportionate amount of repetitive crime and violence.

The scientists were surprised by the high insula activity seen in psychopaths, since this brain region is central to emotion.

However, the stunted response observed in the ventromedial prefrontal cortex and amygdala was consistent with previous studies of psychopathy.

The amygdala, an almond-shaped bundle of neurons deep within the brain, plays an important role in processing emotions such as fear, anger and pleasure.

Most people flinch from seeing others in pain or distress - which serves a useful social purpose, the scientists pointed out.

They wrote in their paper: "The neural response to distress of others such as pain is thought to reflect an aversive response in the observer that may act as a trigger to inhibit aggression or prompt motivation to help.

"Hence, examining the neural response of individuals with psychopathy as they view others being harmed or expressing pain is an effective probe into the neural processes underlying affective and empathy deficits in psychopathy."

Earlier on HuffPost:

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  • Emotional powerplay

    Psychopaths are social chameleons and can change their psychological spots in the blink of an eye if they think they can benefit from doing so. Playing on sympathy is a favourite weapon of choice. Make no mistake: psychopaths are confident, outgoing and mentally resilient, hardly ever, in reality, feeling sorry for themselves. But they are also master manipulators and have no qualms whatsoever about tugging on our emotional heartstrings if it works to their advantage. Sympathy is a powerful motivator – a fact not lost on psychopaths even though they never feel it – and they are extremely adept at eliciting pity and compassion. <strong>WARNING LIGHT</strong>: Consistently poor behaviour with frequent appeals to mitigating circumstances and pleas for support and understanding is one of the psychopath’s most recognizable kitemarks – in both the corporate realm and that of everyday life.

  • Control freak

    Psychopaths are emotional chess players and a psychopathic boss sees his employees merely as pieces on an invisible psychological chessboard: disposable, dispensable, superfluous. Psychopaths love to pick people up, move people round, make people jump just for the sake of it - even if, sometimes, it’s not to their immediate benefit. Unnecessary rearrangements of workspace, the sudden imposition of unsocial working hours, and the promise of favours for dishing the dirt on colleagues are just a few psychopathic favourites. <strong>WARNING LIGHT</strong>: If you’re left scratching your head on yet another occasion as you try to figure out the rationale for your boss’s behaviour – then the answer might be simpler than you think.

  • Charming

    Psychopaths are past masters at making scintillating first impressions and possess an innate gift for making you feel as if you’re the only person in the room. They are brilliant psychologists. They know that, through evolution, our brains are programmed to put a lot of store in initial encounters and so they bank substantial emotional ‘capital’ early in a new relationship by turning on the charm. One psychopath I interviewed put it like this: “Charm is the ability to roll out a red carpet for those you cannot stand in order to fast-track them, as smoothly and efficiently as possible, in the direction you want them to go.” <strong>WARNING LIGHT</strong>: If you suddenly find that the red carpet is rolled up and that the charm fades quickly during subsequent meetings with your boss leaving you feeling confused and vulnerable, you may well have a psychopath on your hands.

  • Parasitical

    Irrespective of whether they play the charm, manipulation or sympathy cards, psychopaths are corporate vampires and are second to none in their ability to take you into their confidence and suck out valuable new ideas that may have been months in the planning. A typical ploy is the use of reciprocity – a powerful tool of influence. A psychopath might open the bidding and ‘confide’ in you some low-level idea of his own in order that you follow suit with something better. Once in the psychopath’s possession however, the idea is then ‘confiscated’ and, somewhere down the line, suddenly becomes ‘theirs.’ <strong>WARNING LIGHT</strong>: If your boss has a habit of taking the credit for work done by others, it might be time to look for work elsewhere.

  • Deceitful

    Psychopaths simply do not live by the same moral code as the rest of us, and experience little guilt or anxiety over telling lies – either to big themselves up, or to dump on others, or both. In fact, it’s their consummate lack of remorse for misrepresenting the facts that is the single biggest contributor to their inordinate capacity for fabrication. They appear plausible and reasonable and their webs of deceit frequently contain a modicum of truth which they rely on as a safety net should their spurious cover stories come under too close a scrutiny. <strong>WARNING LIGHT</strong>: If your relationship with your boss has been plagued by ‘misunderstandings’ and ‘false assumptions’ it might be time to face the real truth.

  • Narcissistic

    Psychopaths are completely driven by their own hard-nosed self-interest. Though they may feign concern for others, appearing warm, considerate and even helpful, such interest is shallow and superficial and merely serves as the foreplay for future exploitation. For psychopath, read “ps-I-chopath.” Psychopathic relationship patterns - in both personal and corporate settings - are stormy and transient. “Friendships” are often terminated without warning, and ties mercilessly severed once an individual ceases to “be of any use.” Add to this an arrogant, grandiose and egocentric interpersonal style and you have on your hands a ruthless ambition machine with no “off “switch. <strong>WARNING LIGHT</strong>: If your boss has been known to fire people for no apparent reason, or has an ostentatious and extravagant profile out of keeping with a more objective assessment of their standing, or has a habit of stealing the limelight…it’s time to leave them to it.

  • Non-stick

    Psychopaths make expert defence attorneys and are supremely skilled at getting themselves off the hook should accusations of incompetence be leveled at them. Not only do they never accept culpability, but they are also extremely adept at manufacturing evidence that lays the blame for their misdemeanours firmly at someone else’s door. Psychopathic bosses have no qualms whatsoever in using their employees as ‘reputation shields’ to safeguard their own status within the company. <strong>WARNING LIGHT</strong>: If your boss has landed you in it through no fault of your own, start asking questions.

  • Oscar nominated

    The brain of the psychopath is wired up in a different way to the rest of ours. In particular, the part of the brain responsible for emotion – the amygdala – is turned down, meaning that psychopaths do not experience the everyday feelings of fear, regret and disgust so familiar to normal folk. But that doesn’t stop the psychopath acting scared, sorry or surprised in order to manipulate others. They are perfectly adept at putting on shows of emotion if it helps them get ahead. A common example is extreme anger in response to a perceived personal insult, an alleged betrayal of trust, or the insufficient demonstration of respect for their authority. But such emotional pyrotechnics are purely for shock-and-awe purposes - coolly calculated psychological bombing raids aimed at minimizing the chances of any future “transgressions.” <strong>WARNING LIGHT</strong>: If your boss is prone to extreme displays of emotion then quickly returns to normal as if nothing has happened, you should start to question whether he really feels anything at all.

  • Non risk-averse

    Imagine someone who has a warped perception of speed: someone who, through some weird trick of nature, perceives things happening at a much slower rate than they actually do. You wouldn’t want to get in a car with them, would you? Well, it’s exactly the same with psychopaths – except for speed, read danger. The neural power-cut in the fear zip code of psychopaths’ brains means that things that would scare the hell out of the rest of us just don’t have the same impact on these ice-cool emotional androids. This, of course, gives psychopaths their enviable sang-froid, their composure under fire – and explains why they often do quite well for themselves in high-wire professions such as the media, finance and certain echelon areas of the military. But it can, at times, also lead to unnecessary risk-taking – and, to return to the speed analogy, can often result in the car veering out of control and crashing off the road as opposed to a speedier journey time (as if we need any reminding with the global financial crisis.) <strong>WARNING LIGHT</strong>: Risky investments, unwise alliances, inappropriate behaviour, risqué comments… if this sounds like your boss you may want to look for another one.

  • Power-hungry

    Psychopaths are attracted to positions of influence in which they can satisfy their need to control and manipulate others. Last year, I launched the Great British Psychopath Survey. The survey is unique: the first of its kind to assess the prevalence of psychopathic traits within an entire national workforce. What would turn out to be the UK’s most psychopathic profession? I wondered. The results made interesting reading. CEOs, media folk, lawyers, surgeons, police officers, the clergy…any line of work which boasts a definitive hierarchical infrastructure and affords a position of power over others which may be wielded with relative impunity is ideally suited to the psychopathic personality. <strong>WARNING LIGHT</strong>: If your boss has a tendency to step on those beneath him but goes out of his way to impress those above him, it’s time to move sideways…to another department or company.

  • X Factor

    Hollywood movies typically portray the psychopath as an intense, menacing figure who makes the hairs on the back of one’s neck stand on end – and there’s evidence to suggest this is true. Psychopaths often do give out a certain ‘aura’ and folk sometimes report experiencing unnerving physical sensations in their presence such as “he sends a chill up my spine” and “he makes my skin crawl.” <strong>WARNING LIGHT</strong>: If you sometimes feel uneasy around your boss, and are uncomfortable being on your own with him for any length of time, trust your gut instinct: GET OUT WHILE YOU STILL CAN!