"Do you like Huey Lewis and the News?" barks Christian Bale's serial killer yuppie Patrick Bateman, in a typically manic scene from the 2000 film American Psycho.
Slipping inside a polythene raincoat, Bateman boogies around his Manhattan apartment, delivering a lengthy and thoughtful commentary about the 80s pop group's finer points, as a drunken co-worker sits dazed in a chair carefully surrounded with newspaper.
Bateman's excited monologue climaxes as he brings the axe down in a bloody frenzy, to a grimly upbeat soundtrack of Hip to Be Square.
Twisted characters like Patrick Bateman - and cult supercriminals Hannibal Lecter (The Silence of the Lambs), Norman Bates (Psycho) and Michael Myers (Halloween) - have come to shape our perception of psychopathy.
The truth, clinical psychologist Dr Armon Tamatea says, is frighteningly more ordinary.
Your nearest psychopath might be your father-in-law, your boss, your financial adviser or even that guy your daughter is thinking about dating.
Just who these people are, how many there are in our society and what helps them blend in are questions that have inspired the Waikato University researcher to launch a major project.
We know that psychopathy is a personality disorder that involves traits such as superficial charm, grandiosity and being deceitful, impulsive and irresponsible.
Perhaps most markedly, psychopaths show a complete lack of empathy and remorse.
Many men with these traits - what we have come to know about this group has largely been through research conducted with males - are also highly likely to have a history of antisocial behaviour.
In New Zealand court decisions since 1985, references to a person being a psychopath - either as a throw-away jibe or from a diagnostic test - have been made 127 times.
A description by the Department of Corrections, borrowed from renowned Canadian criminal psychologist Professor Robert Hare, also mentions a "persistent disregard for social norms and conventions" and a "failure to maintain enduring attachments to people, principles, or goals".
One of the characteristics author Bret Easton Ellis might have got right about his Patrick Bateman was his high-flying businessman persona.
A recent Victoria University study revealed students with higher scores for psychopathy traits tended to opt to study commerce and, to a lesser extent, law.
Hare's book, Snakes in Suits, also explored how psychopaths in the corporate world applied instinctive manipulation techniques to business, to become part of a group sometimes known as the "successful psychopaths".
For Tamatea, these characters were a different breed to some of the many prisoners he assessed in a decade advising the Corrections Department.
Although we don't know how many of our criminals within the prison and court system show psychopathic traits, we can look to international rates that vary between one and 25 per cent of male offenders.
Hare found each of the inmates referred to an experimental treatment programme designed to address institutional violence in men who had extensive psychopathic traits easily met the diagnostic criteria for psychopathy.
Yet all were very different men who did not conform to a particular type, or even stereotype.
"And despite their excessively antisocial histories, many of these men developed quite significant attachments to each other and for no apparent gain," he says.
"It was this human side to so-called psychopaths that is not often discussed or recognised that interested me." Most of what we know about psychopaths has come from offender-based studies, but an emerging body of research has focused on those who had managed to adapt to life in the community.
One of New Zealand's leading experts on the subject, Victoria University's Professor Devon Polaschek, says it's not known exactly what proportion of society is psychopathic and there has never been a community survey to establish a figure.
Now Tamatea wants to build a picture of how prevalent psychopathic traits are in Kiwi communities, which might help us understand how these people have been able to remain invisible and even thrive, despite their challenging personalities.
"It's almost a given that psychopathic individuals incur emotional or even physical harms on others either through interpersonal manipulation, direct aggression or as a consequence of carelessness and irresponsible behaviour," he says.
"I am interested to discover from 'everyday' psychopaths what kinds of environments best 'fit' these individuals, what kinds of social roles they occupy, and what kinds of social strategies and lifestyle choices they make."
It is clear, Tamatea says, that our idea of psychopaths is generally exaggerated, and this can be blamed on movies, TV crime shows, blogs, and even a criminal bias in academic and popular media.
Victoria University Associate Professor of Psychology Marc Wilson agrees.
Psychologically themed crime drama has been "tremendously popular" for the past couple of decades, he says, sparking the rise of TV shows focusing on profilers who specialise in hunting down bad guys often characterised as psychopaths.
"Psychopaths are often portrayed as serial killers, so the two have become a little intertwined in the minds of lay people," he says.
"That said, I imagine that many if not most serial killers would also be characterisable as psychopaths, while it wouldn't be true to say most psychopaths are serial killers."
Indeed, it is possible for people to have psychopathic traits without a criminal history, Tamatea says.
"We must be careful and sensitive when approaching the issue of psychopathy in our community because people have likely developed psychopathic traits in response to early adversity such as child abuse or neglect," he says.
"Psychopaths present as a vulnerable group that make others vulnerable."
Assessing thoroughly for psychopathy is no quick or easy task. It isn't included in the US psychiatry guide Diagnostic and Statistical Manual of Mental Disorders, but schizophrenia and other disorders are.
Auckland University criminal psychologist Dr Gwenda Willis says its conceptualisation as a "disorder" is therefore slightly misleading.
The vagueness surrounding its definition lingers on, despite psychopathy having been flagged perhaps as early as 1833 by James Prichard.
The famed English physician proposed there was a kind of deviant set of behaviours that weren't consistent with what we usually think of as mental illness.
Tamatea says we might be able to go back even further, to 1800, when French physician Phillipe Pinel described a small group of patients who displayed manie sans delire, or "mania without delirium".
These otherwise rational and intelligent individuals of sound mind were shown to behave in irresponsible and self-defeating ways, often with disastrous consequences for themselves and others.
Because deceit and impression management can mask the clinical picture, an emphasis on actual behaviour is today seen by psychologists as a more reliable index.
New Zealand's correction system uses a time-consuming process known as the PCL-R, which involves scoring a person on a range of psychopathic characteristics based on a combination of clinical interview and personal history.
Beyond that, there are self-report screenings of the PCL-R, an index called the Psychopathic Personality Inventory, and the more modern Triarchic Psychopathy Measure, which can assess a person's levels of boldness, meanness and dominance.
Tamatea says part of the definition of mental illness is "personal distress" - something fairly obvious in someone experiencing intense anxiety or a psychotic episode. But psychopaths are set apart by the fact they tended not to suffer, even if those around them do, making them unlikely to seek help unless prompted by the courts.
He describes the "gold standard" approach as drawing together behavioural information from a variety of sources, such as an interview, file information if there is an offence history and observations from other people who know the person well such as a spouse, employer, or probation officer.
"A key issue in this process is not to get too caught up on one or two factors, such as any criminality or a narcissistic personality style, but rather to assess for the whole spectrum of traits," Tamatea says.
"We all know people who may have the gift of the gab, or seek to impress us by dropping names of famous people that they claim to know, regularly shirk their responsibilities like paying bills .
"They may have even committed crimes, amongst other things.
"Although each of these quirks in and of themselves do not necessarily indicate psychopathy, the picture could get more interesting if a lot of these traits start to become apparent in the same person, over time, and across situations."
As a society, Tamatea says, we must be careful to not further marginalise an already marginalised group.
"I recognise that many psychopathic individuals incur real and significant social, economic and human costs by virtue of their behaviour."
He believes there are many whose actions are less harmful - and maybe even advantageous in the right context.
"I want to create opportunities to learn more about this population, what strengths they possess, how to relate and get the best from them, and more importantly, how to reduce the actual and potential harms that they may wreak on us."
Whether psychopaths could be good citizens and be given jobs that allowed them to use their "skills" for common good - a key argument of Robert Smith's 1978 benchmark work The Psychopath in Society - remains to be seen.
Wilson suspects this is a rather naive hope.
"Devon Polaschek often uses Jeremy Renner's character in The Hurt Locker as an example of her model of the psychopath - sure, he defuses bombs and saves lives, but he's also impulsive and egocentric and causes collateral damage.
"It's difficult to imagine where psychopathic traits would be helpful but not also risky."
Move away from traditional treatment
Our view of psychopaths as murderous maniacs isn't the only stereotype that surrounds them - popular belief also dictates they are beyond treatment.
But a recent study by Victoria University Professor of Psychology Devon Polaschek challenges this.
Her review, published in the journal Current Directions in Psychological Science, canvassed academic literature on psychopathy and found evidence to suggest psychopaths could benefit from psychological treatment.
The study suggested psychopathic characteristics, especially those most related to criminal offending, could change over the course of a life and although those with psychopathy were among the hardest for clinicians to work with, treatment caused them to offend less.
Polaschek said psychopaths had sometimes been excluded from criminal justice interventions because of beliefs about psychopathy's "immutability and their untreatability".
But recent findings had opened the way for a revitalisation of research and treatment of psychopathy.
Her research found the PCL-R, a measurement tool used by the Department of Corrections that involved scoring a person on a range of psychopathic characteristics based on a combination of clinical interviews and personal history, had limited previous studies into what the notion of psychopathy was.
"A much more interesting future for treatment research lies in breaking away from this tradition, which hides the surprising degree of disagreement and confusion within the scientific community about what psychopathy is and is not."