8- Simons & Chabris: COGNITIVE Flashcards
Background
Visual attention
The eye may record visual experience by we don’t direct our attention at everything that is recorded by the eye. This kind of selective attention is called selective looking.
Background
Inattentional blindness
2 kinds:
1) Change blindness:
A person fails to notice large changes to objects from one view to the next.
2) Inattentional blindness:
A person fails to perceive an unexpected object when attention is diverted.
Aim(s)
To built on previous research and investigate factors that may affect visual detection rates:
1) The visual similarity of the unexpected object & the attended ones.
2) Task difficulty.
3) The superimposed version of the display versus the live version.
4) The nature of the unusual event.
Design
(Method)
-> Laboratory experiment
-> Independent measures design.
IV
(Method)
16 conditions for this study, enabling a number of different independent variables to be studied:
1) Unexpected event was an umbrella women or gorilla.
2) Film that was transparent or opaque.
3) Task was easy or hard.
4) Ps followed black or white team.
DV
(Method)
Not mentioned in the book - guessed using procedure.
Whether the Ps (observers) noticed the event using a series of questions.
Sample
Self-selected sample of 228 mainly undergraduates from an American University acted as ‘observers’.
I.e., they watched the films.
Some had no reward, others were given a candy bar or a small fee.
In the final analysis only 192 Ps (observers) were used, equally distributed across the 16 conditions.
The remaining 36 Ps (observers) were ruled out because e.g., they knew about the phenomenon beforehand.
A further 12 Ps took part in a controlled observation.
Materials / apparatus
1) 4 videotapes were created of 2 teams throwing a basketball. Each videotape:
-> Lasted for 75 seconds.
-> Had 2 teams with 3 players.
-> Showed players passing the ball from player 1 to 2 to 3 and back to 1 and so on.
2) After 44-48 seconds an unexpected event occurred lasting 5 seconds. A women walked from left to right either holding an umbrella or wearing a gorilla costume.
3) There were 2 styles of video: Transparent (2 teams of actors superimposed) or opaque (all actors filmed at the same time).
Procedure
1) All observers were tested individually and took part in only one of the 16 conditions.
2) Observers were told to watch either the white or black team.
3) Observers were also told that they should keep a silent mental count either of:
-> Total number of passes made by the attended team (easy condition).
-> Total number of bounce passes and aerial passes made by the attended team (hard condition).
4) Immediately after viewing the video observers were asked to write down their count(s).
5) There was a surprise series of questions to determine whether observers noticed the unexpected event:
i - Did you notice anything unusual on the video?
ii - Did you notice anything other than the 6 players?
iii - Did you see anyone else?
iv - Did you see a gorilla / women carrying an umbrella walk across the screen?
6) If observers said yes, they were asked for details. If at any point an observer mentioned the unexpected event, the remaining questions were skipped.
7) After the questioning, observers were asked whether they had ever previously participated in an experiment similar to this or had ever heard of such an experiment or the general phenomenon. The data from observers who said ‘yes’ was discarded.
8) Observers gave informed consent in advance and at the end of the study each observer was debriefed. This included replaying the videotape if requested.
Results
(General / overall)
1) KEY RESULT: 54% of observers did notice the unexpected event, which means that 46% failed to notice it.
2) Answers to the 4 questions were fairly consistent for each observer so they were combined - either a Ps noticed or didn’t notice.
Results
For the 4 IVs
3) Unexpected event was umbrella women or gorilla:
The umbrella women was noticed more (65% vs 44%, p<0.004). This shows that she was more visually salient (distinctive).
4) Film was transparent or opaque:
The unexpected event was noticed more in the opaque rather than transparent condition (67% vs 42%, p<0.001).
5) Task was easy or hard:
The unexpected event was noticed more in the easy condition (64% vs 45%, p<0.009).
6) Observers followed black or white team:
-> Gorilla / black: more likely to notice than those in white (58% vs 27%, p<0.002).
-> Umbrella: Little difference between teams (62% vs 69%, p<0.519).
Results
Other:
- Task difficulty
- Inaccurate counting
- Controlled condition
7) Task difficulty:
The hard condition was shown to be more difficult than easy condition.
Demonstrated by looking at the average standard deviation of the total pass counts for each condition. The SD of the har was much larger (6.77 vs 2.71).
8) Inaccurate counting:
There was no significant correlation (r = .15) between noticing and poor counting, so poor counting could not account for the results.
9) Controlled condition:
Only 50% noticed the event, which is roughly the same as the % that noticed the normal opaque gorilla walking event (42%) under the same task conditions.
Conclusion(s)
1) Observers are less likely to notice unexpected events if these events are visually dissimilar to the events they are paying attention to.
2) Even when the unexpected object passes through the area of attentional focus in the eye (the fovea) it may be undetected.
3) This shows there is no conscious perception without attention.
