Abstract
Simons and Chabris showed observers often miss a salient gorilla walk-through while counting basketball passes — inattentional blindness for dynamic events under load.
Simons, D. J., & Chabris, C. F. (1999). Perception, 28(9), 1059–1074. DOI
Key findings
- Missed gorilla — Roughly half of observers failed to report the gorilla when attention was tied to the counting task.
- Attention budget — Focused tasks consume awareness — obvious motion can vanish without hypocrisy.
- Dynamic events — Blindness holds for moving surprises, not only static change blindness demos.
- Surprise on replay — Many insist they would have noticed — the clip proves otherwise.
Limits
Lab basketball/gorilla demos — vivid, not every workplace layout.
Application
When you insist you would have seen the obvious — intense focus on one job can erase salient motion elsewhere. See Reticular Activating System.