This article, details how computer scientists from the U.S. and Britain have created an artwork whose palette will correspond to facial cues of an observer.
Oddly enough, the painting will turn somber when a frown is perceived or become playful when smiles are observed. I think they got it backwards; they should have made gruesome scenes when a face is observed to happy and vice versa... Just to keep the observers on the edge. Plus, do we always have to reinforce that happy is red and yellow, and sadness is blue and purple?
What I am waiting for is the ultimate marketing gimmick: the painting that changes all the time until it picks up on a smile, upon which time it stays stagnant. That way- the painting will be individually pleasant to everyone.