Why watching someone itch makes you scratch
Last updated on 2/2/2015 Print this page
12 November 2012
Have you ever experienced the feelings of itchiness while
watching someone else scratch? Scientists from the universities of
Hull and Sussex have found the part of the brain responsible for
‘contagious’ itching – and discovered why some people are more
prone to it than others.
Psychology lecturer Dr Henning Holle worked with a team of
researchers from the University of Sussex and Brighton and Sussex
Medical School in a bid to determine why some people are
particularly vulnerable to itchiness when they see others
scratching. Healthy volunteers filled in personality questionnaires
and then underwent Functional Magnetic Resonance Imaging (fMRI)
scans while being shown short videos of people either tapping or
scratching parts of their arms and chest.
The results, published today (November 12, 15.00 EST) in the
journal PNAS, showed that, while contagious itch is experienced by
most people – around two-thirds of those involved in the study
actually scratched themselves while watching the video – people who
experience more negative emotions are more susceptible to it than
The researchers also correlated the volunteers' tendency to
scratch with activity in several brain regions previously
identified as part of the 'itch matrix.' Additionally, it is
reported that the activity noted in three specific regions of the
brain could be linked to subjective ratings of itchiness
It is thought that this new information could be used to help
people suffering from chronic itching sensations where there is no
underlying dermatological cause.
Dr Henning Holle, who led an interdisciplinary team with
researchers from Psychology, Computer Science and Psychiatry, said
“Almost everyone has felt that urge to scratch when watching
someone else, but no-one has ever really known why.
“It had previously been thought that empathy was responsible.
But we found that neuroticism - a measure of the tendency to
experience negative emotions - was positively linked to contagious
itch. Highly neurotic people are known to be highly emotionally
reactive and vulnerable to stress. We found that participants with
higher neuroticism scores are also the ones that are more easily
‘infected’ by contagious itch.
“Our observed link between activity in prefrontal cortex and
neuroticism might reflect that the emotionally more stable
participants, with low neuroticism scores, are less susceptible to
contagious itch, because they are better at suppressing the
irrelevant itch sensation arising from observing someone scratch
The full report ‘The Neural Basis of
Contagious Itch and Why Some People are more Prone to it’ by Dr
Henning Holle et al. can be read in the prestigious PNAS journal
after November 12.