The Affective Computing Research Group, based at the Massachusetts Institute of Technology, is working on computers that can read facial expressions and track basic states like confusion, liking or disliking. Wearable devices, such as electronic bracelets, can detect stress or excitement by measuring minimal changes in the sweat level.

The applications of this technology are wide ranging. Medically, it could help people with autism spectrum disorders to read emotions; commercially, it could be used to evaluate ads by tracking viewers’ emotional response. Developers also say it could have important implications for social movements like the Egyptian revolution.