Biased: Uncovering the Hidden Prejudice That Shapes What We See, Think, and Do

by Jennifer L. Eberhardt

Perhaps the most famous demonstration of selective attention was developed by two cognitive psychologists named Daniel Simons and Christopher Chabris. The demo involves asking people to watch a silent, thirty-second video clip of two teams of people (one in light-colored shirts, the other in dark-colored shirts) passing around a basketball. Unsuspecting viewers are asked to count the exact number of passes made by the team in the light-colored shirts. People are so focused on accurately counting the number of passes that more than half of them completely miss the gorilla in the room: someone in a gorilla suit enters the scene on the right, pauses in the middle for a chest pound, and then exits the scene on the left. Their attention is so focused on the task at hand that their brain records the gorilla as irrelevant. The effect is so strong that those who miss the gorilla are shocked later by the realization that they never saw the giant animal enter the scene.