JOIN USResearchers from the University of Glasgow showed volunteers images of people’s faces displaying different emotions such as happiness, fear and surprise.
In a series of trials, parts of the images were randomly covered so that, for example, only the eyes or mouth were visible. Participants were then asked to identify the emotion being displayed while electrodes attached to the scalp measured the volunteers’ brainwaves.
The scientists were able to show that brainwaves varied greatly according to which part of the face was being looked at.
“Beta” waves, with a frequency of 12 hertz, carried information about the eyes, while four hertz “theta” waves were linked to the mouth. Information was also encoded by the phase, or timing, of the brainwave, and less so by its amplitude, or strength.
Professor Philippe Schyns of Glasglow, who led the study, said: “It’s a bit like unlocking a scrambled television channel. Before, we could detect the signal but couldn’t watch the content—now we can.”
Schyns said the study revealed how the brain tuned into different brainwave patterns to code different visual features.