Seeing someone scratch an itch 'makes you itchy too'
Seeing someone scratch an itch could make you feel itchy too, a study suggests.
The British Journal of Dermatology paper looked at whether images such as those of others scratching or ants crawling on skin, made people scratch.
The study of 30 people asked them how they felt looking at these and "non-itch" images - and found visual cues did provoke a "scratch response".
Experts said the work could help understand skin disorders.
The participants in the study, overseen by researchers at Liverpool John Moores University and the University of Manchester, were shown a range of images; insects such as ants and midges on and off the skin, skin conditions or neutral images such as butterflies and healthy skin.
For each picture, people were asked how itchy they felt. The researchers also checked how often they scratched themselves while looking at the images.
It was found that visual cues did provoke the sensation of itch in people - and made them scratch.
And, in particular, it was watching another person scratching - rather than seeing the cause of an itch - that made people feel itchy themselves.
Prof Francis McGlone, a cognitive neuroscientist at Liverpool John Moores University, who led the study, said: "The results suggest that, whereas the sensation of itch may be effectively transmitted by viewing others experiencing itch-related stimuli on the body, the desire to scratch is more effectively provoked by viewing others scratching."
He added: "Our findings may help to improve the efficiency of treatment programmes for people suffering from chronic itch.
"Itch has far more serious psychological consequences than people give it credit for.
"If you have chronic itch your life is blighted, but if you're unable to scratch that itch - or if you do scratch it - it gets worse and worse."
A spokeswoman for the British Association of Dermatologists said: "Itch is often the worst symptom for people with skin disorders, and any research into its causes that may lead to new methods of alleviation will be greatly welcomed by the millions of skin patients.
Another study, recently published in Proceedings of the National Academy of Sciences, used brain scans to show the same parts of the brain are activated when watching someone else scratch an itch as when someone does it themselves.
That team, including experts from Hull University, suggested that the activation of these areas could explain itching disorders where there is no physical cause.
Lead researcher Dr Henning Holle, of Hull University, said: "It was particularly interesting to see that contagious itch is not only elicited by observing someone scratching.
"Simply seeing potentially itchy stimuli, for instance ants crawling on the ground, seems to be enough to induce feelings of itchiness in one's own body.
"This suggests that a process of motor mimicking alone cannot explain contagious itch."