Next, they placed a large vertical mirror in front of the itchy arm, blocking off the subject’s view of their right arm and reflecting back the non-itchy one in its place . They asked the volunteers to look only at the reflected limb in the mirror, whilst a member of the team again scratched each arm.

This time the participants felt relief when the unaffected, reflected arm was scratched.

Although the effect was relatively weak – the relief from mirror scratching is about a quarter of that from scratching the real itch – the study shows that visual signals to the brain can override messages from the body if there is a mismatch between them.