Glossary
Inattentional blindness
What is inattentional blindness?
Inattentional blindness is a failure to notice an unexpected, visible object or event while attention is engaged elsewhere. Looking toward a location does not ensure that a person will consciously report everything there.
The invisible gorilla experiment
Simons and Chabris’s 1999 study asked people to monitor basketball passes while an unexpected event occurred, including a person in a gorilla suit passing through the scene. Some observers missed the gorilla while concentrating on the task. Detection depended on the task’s difficulty and the unexpected object’s similarity to attended objects.
Example in medical imaging
In a 2013 study of 24 radiologists, 20 did not report a gorilla inserted into CT images during a lung-nodule search. Most of those who missed it had looked at its location. This showed that expertise did not prevent this failure of awareness.
The 20 out of 24 result (83%) describes a failure to detect an artificial, unexpected gorilla in that study. It is not a rate of missed lung nodules or clinical errors. Eye position also should not be confused with conscious awareness.
Why it matters
Putting something in plain view is not the same as making sure it gets noticed. In driving, screening or interface design, consider what the person is actively looking for and what else competes for attention. Expertise does not make attention unlimited.
Inattentional blindness vs. change blindness
Unlike change blindness, the central issue is noticing an unexpected item, rather than comparing a scene before and after a change. The result does not establish that all unnoticed information receives no processing.