The brain is susceptible to inattentional blindness change blindness or selective looking, as it is called. This was demonstrated in a study by Daniel Simons and Christopher Chabris of Harvard. A person in a gorilla suit walked into the center of a ball game and half of the observers watching the video did not notice the gorilla. The brain selects the least amount of information necessary to effectively respond to a situation, which is especially useful in emergencies. Sometimes it overlooks crucial information, however, which may help to explain the reason that teenagers are so prone to accidents. (Simons, D.M., and C. F. Chabris. “Gorillas in our midst.” Perception 28: 1059-1074. 1999)