"The best and most beautiful things in the world cannot be seen or even touched. They must be felt with the heart." If this observation by Helen Keller is true, then robots would be destined to miss out on the best and beautiful. After all, they're great at sensing the world around them, but they can't turn that sensory data into specific emotions. They can't see a loved one's smile and feel joy, or record a shadowy stranger's grimace and tremble with fear.
This, more than anything on our list, could be the thing that separates man from machine. How can you teach a robot to fall in love? How can you program frustration, disgust, amazement or pity? Is it even worth trying?
Some scientists think so. They believe that future robots will integrate both cognitive emotion systems, and that, as a result, they'll be able to function better, learn faster and interact more effectively with humans. Believe it or not, prototypes already exist that express a limited range of human emotion. Nao, a robot developed by a European research team, has the affective qualities of a 1-year-old child. It can show happiness, anger, fear and pride, all by combining postures with gestures. These display actions, derived from studies of chimpanzees and human infants, are programmed into Nao, but the robot decides which emotion to display based on its interaction with nearby people and objects. In the coming years, robots like Nao will likely work in a variety of settings -- hospitals, homes and schools -- in which they will be able to lend a helping hand and a sympathetic ear.