A-01 · Attention & Perception
Count what you're told to count, and discover what your attention deletes from the world.
Experimental design
Between-subjects (single critical trial); unexpected-stimulus detection
Inattentional blindness
Failure to report a salient, fully visible unexpected object when attention is engaged elsewhere
Attentional load
Difficulty of the counting or tracking task imposed on the observer
Unexpected stimulus
Object not described in pre-trial instructions and absent from practice
Inattentional blindness
Failure to notice an unexpected object in plain view because attention is occupied by another task (Mack & Rock, 1998; Simons & Chabris, 1999).
Change blindness
Failure to detect a change between two displays; distinct from inattentional blindness, which concerns a single display (Simons & Rensink, 2005).
Attentional set
The task-defined filter that determines which features or objects receive processing resources.
Difficulty
IntroEstimated time
8 minutes
Paradigm
Inattentional blindness
First published
1999
Attention is a spotlight, not a floodlight. When your visual system commits to one task, unexpected objects, even large, obvious ones, can pass through your field of view without ever reaching awareness.
In 1999, Daniel Simons and Christopher Chabris asked participants to count basketball passes between players in white shirts. Halfway through the video, a person in a gorilla suit walked through the scene, faced the camera, thumped its chest, and left. Roughly half of all viewers never saw it. The study became one of the most cited demonstrations in cognitive psychology because it overturned the intuition that we see what is in front of our eyes. Seeing requires attention, and attention is a scarce resource allocated by task goals.
Simons, D. J., & Chabris, C. F. (1999). Gorillas in our midst: Sustained inattentional blindness for dynamic events. Perception, 28(9), 1059–1074.