Want to know an effective way to reduce pain from burns? Cover the affected red area, so you are unable to look at it. Ideally, use a blue bandage. Painfully hot stimuli applied to red skin feel more painful than applied to blue skin, a new research article published in Frontiers in Human Neuroscience shows.

The scientists, Matteo Martini, Daniel Perez-Marcos and Maria Victoria Sanchez-Vives from the University of Barcelona, used immersive virtual reality in combination with the application of real heat stimuli to the wrists of experimental subjects. Participants saw their virtual arms get increasingly red, blue, or green as the heat rose, and indicated, by pressing a button, when the sensation became painful. In an additional experimental condition, a gray dot close to the virtual arm became red as the temperature increased, but the color of the arm itself remained unaltered.

The results showed that subjects experienced pain earlier (that is, at lower physical temperatures) when the arm was red than when it was blue.

Also, the experience of increased pain was not associated to seeing red per se, but it mattered whether the color was on the body or not. A patch of red near --but not on-- the virtual arm resulted in significantly less pain than that recorded with the arm itself becoming red.

So much for looking at life through rose-colored glasses.

See more pain illusions in our new article in Scientific American Mind, in the September 2013 print edition.