The beginnings of emotion detection technology will be demonstrated at the Royal Society Summer Science Exhibition on July 3-6. By analyzing facial expressions, software can determine a person's mood and respond accordingly. This information could be used to return specialized results from a web search, change the response of the car you're driving, or - you guessed it - provide targeted advertising content. The software performs 24 static and dynamic measurements of the human face to recognize about 20 different emotional states.