When the creators of the children’s television show Sesame Street wished to know whether preschoolers would actually watch it, their head of research, Ed Palmer, set up a room with a television monitor showing segments from the show. On a nearby screen, Palmer projected slides of various images; the slides changed every seven-and-a-half seconds. Then he brought small children in and waited to see if the children focused on the Sesame Street segments or the still pictures. Only segments that elicited attention from many preschoolers ended up on the air. As a result, the producers discarded segments that they had intended to run and created new characters to hold children’s attention. After three or four seasons, nearly every segment held the attention of at least 85% of the children.