Certain criminals with tattoos are more likely to suffer from anti-social personality disorder (ASPD), new research from the US has revealed.
A study of forensic psychiatric patients in Michigan - half of whom were deemed unfit to stand trial and half of whom were found not guilty through insanity - revealed that 73% of the survey group that were tattooed also exhibited strong signs of ASPD.
Sufferers of the disorder are characterised by a lack of empathy and shallowness and are prone to pathological lying, cheating, stealing, physical aggression and drug abuse.
The research also revealed that the inmates who had tattoos were more likely to have suffered sexual abuse, abused substances or attempted suicide.
Dr William Cardasis, of the Michigan Centre For Forensic Psychiatry, conducted the research. He said: "Our findings suggest that forensic psychiatric inpatients with tattoos are significantly more likely to suffer from ASPD than those without tattoos, and patients with ASPD were also significantly more likely to have higher numbers of tattoos, a larger percentage of their body covered with tattoos, and tended to have tattoos in more visible locations."
He added: "I hope this provides clues for clinicians to look for ASPD in forensic psychiatric patients with tattoos, and also to look for signs of suicide attempt, substance abuse, and sexual abuse."
Glasgow academics have also been conducting their own research into tattoos. Kevin Durkin, a psychologist at Strathclyde University, has been leading projects that found tattooed students have poorer study skills than the non-tattooed, that children are scared of people with tattoos and a heavily tattooed person is more likely to have substance abuse problems than a person with none.
He said: "I'm not saying tattoos cause a problem, but they may be associated with it.
"Some can indicate a confrontational mode of behaviour. I met one guy who tried to tattoo f*** off' across his forehead; he used a mirror to write it, so he got the words back to front.
"I must add that we must be careful not to stereotype everyone with tattoos: most people that have them aren't simply going to erupt into violence."
But tattoo aficionados have reacted angrily to the research.
Kenny Mitchell, owner of Land Ahoy Tattoos in Glasgow, studied at art school before starting his business. He said: "You could also say that all these people in this survey have a short back and sides haircut. Does that make them anti-social? I'm sure you could find a lot more that these people have in common than a tattoo.
"This research highlights the image people like me are trying to get away from. It's an old-fashioned way of thinking, that only criminals, bikers and sailors have tattoos. Just look at Beckham or film stars - this is the most popular tattoos have ever been. By the time our generation is old, every single nursing home in the country will be filled with tattooed people."
Stewart Ross, a Glasgow-born psychologist who now teaches in Birmingham, has his entire back tattooed. He said: "This research is cack. You're basically lumping everyone who has a tattoo and happens to be in a forensic psychiatric unit into one kind of club.
"Without taking into account what the tattoos are, this is worthless research. We still don't know whether these people were tattooed before they went forensic.
"Having a tattoo doesn't make you a criminal," he insisted.