Psychologists have revealed the tell-tale sign that could indicate a person is a psychopath.
Among the many infamous people who are considered to be psychopaths, are serial killers Ted Bundy, Fred West, and Richard Ramirez.
Although it’s not possible to gauge whether someone is a psychopath simply by looking at them, there are some interesting signs to be aware of.
Researchers at Cardiff and Swansea Universities examined the effect of showing unpleasant images to offenders who are psychopathic and offenders who aren’t.
They saw a marked difference in the eyes of the two groups when they looked at the pictures.
They noted that the psychopathic participants had a unique reaction to horrific scenes – their pupils did not widen.
In contrast, pupils of non-psychopaths dilate when they see upsetting or distressing images as part of a natural response.
This look is typically known as the ‘psychopathic stare’ or ‘psychopathic eyes’ – and can reflect a cold attitude towards events most people would find distressing.

Ted Bundy, an American serial killer who confessed to 28 murders, but is believed to be responsible for more than 100, was considered to be a psychopath. He was executed by electric chair in January 1989 in Florida (pictured in 1978)
Speaking when the research was published in 2018, lead author, Dr Dan Burley, from Cardiff University’s School of Psychology, said: ‘Our findings provide physical evidence of an emotional deficit common to psychopathic offenders.
‘The pupil has long been known to be an indicator of a person’s arousal.
‘Card sharks have learnt to look carefully at the eyes of their opponents to gauge if they have a great hand, and many an astute salesperson knows to up their price if your eyes reveal your excitement at their product.
‘Likewise, the pupil usually dilates when an image shocks or scares us.
‘The fact that this normal physiological response to threat is reduced in psychopathic offenders provides us with an obvious physical marker for this condition.’
Pupil dilation in the eyes the psychopaths was abnormal when looking at distressing scenes.
However, researchers were surprised to see that their pupils dilated when looking at positive pictures, just as the pupils of non-psychopaths do.
As a result of these findings, the scientists suggested this indicates that psychopathy is not associated with an overall difficulty in responding to emotion.

Serial killer Fred West, who has been described as a psychopath, is believed to have killed at least 12 people. He didn’t stand trial for the murders as he took his own life in 1995 before the case was tried (pictured with Rose West)

Richard Ramirez, also known as the ‘Night Stalker’, was convicted of 13 murders in 1989. While on death row in in San Quentin prison in California, he died of natural causes in 2013, aged 59 (pictured during a court appearance in Los Angeles in 1985)
Rather, they said, it suggests a specific insensitivity to threatening information.
Professor Nicola Gray is a clinical and forensic psychologist from Swansea University, who provided clinical supervision for the project.
Speaking at the time, she said: ‘This is one of the first times we have objective, physiological, evidence of an emotional deficit underpinning the offending behaviour of psychopathic offenders that does not depend on invasive methods or expensive equipment.
‘We hope to be able to develop this methodology to assist with clinical assessment and intervention in offender populations.’
Professor Robert Snowden from Cardiff University said that many psychopathic offenders appear to be bold, confident, and can act in cold-blooded manner.
He added: ‘It’s much easier to act bold if you have no feelings of fear, and to be cold-blooded if there is no emotion to get in the way of the act.’
The term psychopath is not a diagnosis, and while some people believe it is the same as antisocial personality disorder (ASPD), according to Dr David Tzall, a licensed psychologist, they are not the same thing.
Speaking to Psych Central, he said that the two conditions are ‘similar in scope but different in terms of details’ describing ASPD as ‘a diagnosable personality disorder characterised by a pervasive pattern of disregard for the rights of others, the safety of themselves and others, impulsivity, and socially accepted norms and rules’.
Meanwhile, he said: ‘Psychopathy is a personality construct that describes a set of interpersonal, affective, and behavioural traits that are similar to those observed in ASPD.’