Lumitouch system consists of a pair of interactive picture frames which measure the distance of a person to the picture and transmit the distance as the brightness of an LED on the remote frame. People can also squeeze the sides of the picture frame. The squeeze pressures are transmitted as brightness of a particular color. The top three sides of the picture frame are mapped to different colored lights. The display varies depending on the squeeze attributes (where, how hard, and how long the user squeezed).
Source: Chang, A., Resner, B., Koerner, B., Wang, X., and Ishii, H. 2001. LumiTouch: An Emotional Communication Device. In Extended Abstracts on Human Factors in Computing Systems (CHI’01). ACM Press, 313–314.
http://web.media.mit.edu/~anjchang/PORT/LumiTouch.html
