simons and chabris (1999) visual inattention Flashcards
research method
• This is primarily a laboratory experiment that used an independent measures design.
• The independent variables (IVs) were whether the participant took part in:
(i) The Transparent/Umbrella Woman condition
(ii) The Transparent/Gorilla condition
(iii) The Opaque/Umbrella Woman condition
(iv) The Opaque Gorilla condition
(From left to right, top to bottom: Transparent/Umbrella Woman, Transparent /Gorilla, Opaque/Umbrella Woman, Opaque/Gorilla)
• For each of the four displays there were four task conditions:
(i) White/Easy
(ii) White/Hard
(iii) Black/Easy
(iv) Black/Hard
Overall there were therefore 16 individual conditions.
• The dependent variable (DV) was the number of participants in each of the 16 conditions who noticed the unexpected event (Umbrella
Woman or Gorilla).
• A controlled observation was subsequently conducted in which participants watched a different video and had to attend to the White team
and engage in the Easy monitoring task.
Materials
• Four video tapes, each 75 seconds in duration were created.
• Each tape showed two teams of three players, one team wearing white shirts, the other black shirts.
• Players moved around in a relatively random fashion in an open area infront of a bank of three elevator doors.
• The members of each team passed a standard orange basketball to one another in a standardised order: player 1→ player 2 → player 3 →
player 1. Passes were either bounce or aerial. Players would also dribble the ball, wave their arms and make other movements consistent with
their overall pattern of action.
• After 44-48 seconds of action either of two unexpected events occurred: in the Umbrella-Woman condition, a tall woman holding an open
umbrella walked from off camera on one side of the action to the other, left to right. (The actions of the players, and the unexpected event
were designed to mimic the stimuli used in previous research by Neisser and colleagues.) In the Gorilla condition, a shorter woman wearing a
gorilla costume that fully covered her body walked through the action in the same way. In either case, the unexpected event lasted 5 seconds,
and the players continued their actions during and after the event.
• There were two styles of video: in the Transparent condition, the white team, black team and unexpected event were all filmed separately , and
the three video streams were rendered partially transparent and then superimposed by using digital video-editing software. In the Opaque
condition, all seven actors were filmed simultaneously and could thus occlude one another and the basketballs. (This required some rehearsal
before filming to eliminate collisions and other accidents and to achieve natural-looking patterns of movement.)
• All videos were filmed with an SVHS video camera and were digitised and edited using a nonlinear digital-editing system.
• In a separate Opaque-style video recording, the gorilla walked from right to left into the live basketball-passing event, stopped in the middle of
the players as the action continued all around it, turned to face the camera, thumped its chest, and then resumed walking across the screen.
sample
For the experiment: 228 participants (referred to as ‘observers’ throughout the original study), almost all undergraduate students. Each
participant either volunteered to participate without compensation, received a large candy bar for participating, or was paid a single fee for
participating in a larger testing session including another, unrelated experiment.
• NB: data from 36 participants were discarded so results were used from 192 participants. These were equally distributed across the 16
conditions.
• For the controlled observation: 12 different participants watched the video in which the gorilla thumped its chest.
outline- procedure
Twenty-one experimenters tested the participants. To ensure standardisation of procedures a written protocol was devised and reviewed with
the experimenters before data collection was begun.
• All participants were tested individually and gave informed consent in advance.
• Before viewing the video tape, participants were told they would be watching two teams of three players passing basketballs and that they
should pay attention to either the team in white (the White condition) or the team in black (the Black condition).
• They were told to keep either a silent mental count of the total number of passes made by the attended team (Easy condition) or separate
silent mental counts of the number of bounce passes and aerial passes made by the attended team (Hard condition).
• After viewing the video tape and performing the monitoring task, participants were immediately asked to write down their count(s) on paper.
• They were then asked the following additional questions:
(i) While you were doing the counting, did you notice anything unusual in the video?
(ii) Did you notice anything other than the six players?
(iii) Did you see a gorilla/woman carrying an umbrella walk across the screen?
• After any “yes” responses, participants were asked to provide details of what they noticed. If at any point a participant mentioned the
unexpected event, the remaining questions were skipped.
• After questioning, participants were asked if they had previously participated in a similar experiment, heard of such an experiment or heard of
the general phenomenon. If they said “yes” they were replaced and their data were discarded.
• Participants were debriefed; this included replaying the video tape on request.
• Each testing session lasted 5-10 minutes.
conclusions
Individuals have a sustained inattentional blindness for dynamic events.
• Individuals fail to notice an ongoing and highly salient but unexpected event if they are engaged in a primary monitoring task.
• Inattentional blindness is a ubiquitous perceptual phenomenon (rather than an artefact of particular display conditions).
• The level of inattentional blindness depends on the difficulty of the primary task.
• Individuals are more likely to notice unexpected events if these events are visually similar to the events they are paying attention to.
• Objects can pass through the spatial extent of attentional focus (and the fovea) and still not be ‘seen’ if they are not specifically being attended
to.
• There is no conscious perception without attention.
