Can itch-related visual stimuli provoke an itch response?

Abstract

Itching is a common subjective sensation experienced on the skin and is associated with the desire and impulse to scratch. We tested whether visual cues could generate feelings of itch and provoke a scratch response in healthy volunteers. A secondary aim was to assess whether certain pictures were more effective in evoking sensations of itch. Thirty participants viewed static images that could either be itch-related (i.e., viewing ants or skin conditions) or neutral (viewing butterflies or healthy skin). These were further separated by picture type: ‘skin contact’ (i.e., ants crawling on the skin or a butterfly sitting on the hand); ‘skin response’ (i.e., scratching an insect bite or washing the hands) or ‘no skin’ (simply viewing midges or birds flying). The results indicate that the sensation of itch was successfully generated using itch-related pictures in terms of significantly higher self-reports of itch in answer to the questions ‘how itchy do you feel?’ and ‘how itchy do you think the person in the picture feels?’ compared to viewing neutral pictures (). In addition, participants scratched themselves significantly more when viewing itch-related pictures compared to neutral (). The picture type also had an effect upon these measures with more scratching behaviour recorded when viewing pictures depicting others scratching (). This study demonstrates the impact of visual cues on the sensation of itch and the scratch response and may provide preliminary evidence linking contagious itching to the mirror neuron system and the effectiveness of itch-inducing stimuli as a way to probe social communication.