It is quite fascinating how people can focus at a task at hand and totally exclude everything else in their surroundings. A study carried out by Daniel Simons at Harvard University illustrates this phenomenon very well. A number of volunteers watched a 30-second video starring three basketball players wearing black T-shirts and three wearing white ones. The viewers were told to count the number of passes made by one of the teams. Halfway through the film, a man dressed as a gorilla jumped into the middle of the picture, beat his chest at the camera, and walked away. Afterwards the viewers where asked whether they had seen anything unusual. Astonishingly, only a very few put their hand up. The rest had been so fixated on counting the passes that they completely missed the hairy interloper.