Glossary
Change blindness
What is Change Blindness?
Change blindness is a failure to notice a difference between views of a visual scene. It is often demonstrated when the visual signal that would normally draw attention to the change is interrupted or masked.
The Flicker Experiment
Rensink, O’Regan, and Clark’s 1997 experiments alternated an original scene and a modified version with brief blank intervals between them. Participants could struggle to identify even large, repeated changes. A useful verbal cue made detection faster.
A related but different phenomenon
The unexpected gorilla study demonstrated inattentional blindness: missing an unexpected object while attending to another task. The difference matters: the gorilla is an unexpected object, while a change-blindness task asks people to detect a difference between views.
Both findings show limits to visual awareness. They do not mean that every unattended detail is entirely unprocessed.
Why Change Blindness Matters for Design
If an interface changes while a person is looking elsewhere, making the change visible may not be enough to get it noticed. The practical question is whether users detect the change during the task they are actually doing. That needs testing in the interface; the laboratory result does not guarantee a particular design will succeed or fail.