Wednesday, September 1, 2010
Beware of invisible gorillas
People cannot pay attention to everything they see. When you use an information graphic in a presentation, you should let your audience know where they should focus their attention. On August 3rd Dave Paradi showed how to reveal one portion at a time.
This year two psychologists, Christopher Chabris and Daniel Simons published a book called The Invisible Gorilla and other ways our intuitions deceive us. The first chapter is titled “I Think I Would Have Seen That.” It discusses inattentional blindness and eyewitness testimony. Page 6 describes how:
“When people devote their attention to a particular area or aspect of their visual world, they tend not to notice unexpected objects, even when those unexpected objects are salient, potentially important, and appear right where they are looking.”
They ran an experiment in which subjects were shown a video as a Selective Attention Test. Their subjects were asked to count how many times a basketball was passed by one team of three people. Half the subjects missed that the video also had a person in a gorilla suit walk by and thump its chest. A follow up video shows the related Monkey Business Illusion. They also did a Door Study in which a person was asked to give directions to a stranger outdoors on a college campus. Again, half the subjects did not notice that the stranger had been replaced when two people walked between them carrying a door.
London Transport has a series of commercials about being aware of cyclists. One contains a Phone Joke Test.
Back when I was in college some other psychologists at Carnegie Mellon University did a similar gorilla experiment. During a lecture a person in a gorilla suit ran into the room and pretended to shoot the lecturer. Then students were quizzed about what they just had witnessed. One question asked what type of firearm was used. Some witnesses said it was a revolver. The gorilla actually had been armed only with a banana. The gunshot sound effect was provided by another experimenter with a starter pistol.