What happened
A grid of instruments alternated with a modified copy, separated by a blank flash. You searched, cell by cell, until the changing element was found. Your search time per set size traces how much of the scene you could hold and compare at once.
Why it happened
The blank frame masks the motion transient that would normally summon attention to the change. Without that signal, you must load each region into visual short-term memory and compare across the flicker, a slow, serial, capacity-limited process.
Experimental design
Research protocol
Within-subjects; flicker paradigm with masked motion transients
- Independent variable (IV)
- Presence and duration of an inter-stimulus blank (ISI) between original and modified scenes
- Dependent variable(s) (DV)
- Number of alternations until change detected
- Search time (seconds to correct localization)
- Measured constructs
- Visual short-term memoryFocused attentionScene representation
- Operational definitions
Change blindness
Failure to notice a large visual change across successive views of a scene
Motion transient
Low-level signal produced when a region changes luminance or position between frames
Flicker paradigm
Rapid alternation of pre-change and post-change images separated by a blank mask
- Key terms
Transsaccadic integration
Combining information across eye movements; change detection often fails when transients are masked.
Mudsplash
High-contrast distractors that do not cover the change but still impair detection (O'Regan et al., 2000).
Change blindness blindness
Metacognitive overconfidence in one's ability to detect changes (Levin et al., 2000).
The original experiment
Year
1997
Researchers
Ronald Rensink · Kevin O'Regan · James Clark
Sample
Repeated-measures search across dozens of natural scenes
Key finding
With a blank inserted between frames, change detection required an average of over 10 alternations even for central changes.
Rensink, R. A., O'Regan, J. K., & Clark, J. J. (1997). To see or not to see: The need for attention to perceive changes in scenes. Psychological Science, 8(5), 368–373.
Where this shows up in the world
Interface design: state changes without motion cues go unnoticed by users
Aviation and control rooms: silent mode changes are a documented accident factor
Film continuity errors survive because audiences cannot track unattended detail
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