The gorilla that attention edited out

Halfway through a ball-passing task, a person in a gorilla suit walks into view, beats their chest, and leaves. Many viewers counting passes never see it. Christopher Chabris and Daniel Simons made the demonstration famous, but the surprise is not poor eyesight. It is that attention selects. A vivid scene can reach the eyes without becoming part of the scene a person consciously reports.

The experiment does not prove that people miss half of ordinary life, and later replications produce different rates as expectations change. Its bounded lesson is more useful: looking directly at something is not the same as noticing it. Concentration improves one task partly by suppressing competitors—including the one nobody thought to expect.