simons and chabris

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  • Simons and Chabris
    • Theory
      • Focused visual attention: everyday life presents more objects than an individual can respond towards. Attention is necessary to detect change
      • Change blindness: people often don't detect large changes to their environment (particularly if the change isn't the centre of attention). The change is only noticed if the object has focused attention
      • Inattentional blindness: attention is diverted to another object or task. Observers often fail to perceive an unexpected object
      • Visually demanding tasks ‘load’ the brain’s attention and individuals become blind to distractions
    • Background
      • Previous results showed that the majority of observers did not report seeing unexpected events despite being clearly visible
      • One goal of this study was to revive the empirical approach used before and to build on classic studies
      • For this study several video segments were filmed. A large number of observers were asked to watch the videos and answer questions about the unexpected events
    • Research method
      • Lab experiment with independent measures
      • IVs: ps' condition (transparent/ umbrella, transparent/ gorilla, opaque/ umbrella or opaque/ gorilla)
      • There were 4 task conditions/ videos: black/hard, black/easy, white/hard and white/easy
      • There were 16 conditions in total
      • DV: no. of ps' who noticed the unexpected event (umbrella/ gorilla)
      • A white/easy control was used
      • The videos were 75s long and showed two teams of three players moving relatively randomly
      • An orange basketball was passed in a standardised order: 1? 2 ? 3 ? 1. Passes were bounce or aerial. Players would also make other movements
      • After 44-48s the unexpected event occurred
      • Umbrella: a tall woman holding an open umbrella walked from off camera, left to right. The event lasted 5s, and the players continued
      • Gorilla: a short woman wearing a fully covering gorilla costume walked through the action left to right. The event lasted 5s, and the players continued
      • Transparent: conditions were filmed separately, and the three videos were rendered partially transparent/ superimposed together
      • Opaque: all 7 actors were filmed together. This was practised
      • In a separate Opaque video, the gorilla walked from right to left, stopped in the middle of the players, faced the camera, thumped its chest, and carried on 
    • Sample
      • 228 ps', nearly all undergrads,  volunteered to participate for nothing/ received a large candy bar/was paid a single fee if they were part of another, unrelated experiment. Ps' were equally distributed across the conditions
      • Data was only collected for 192 ps'
      • Controlled: 12 ps' watched the gorilla thump its chest
    • Procedure
      • 21 experimenters tested the ps'. To standardise a written protocol was devised/ reviewed before data was collected
      • All ps' were tested individually/ gave informed consent
      • Ps' were told they would be watching people playing basketball and that they should pay attention to either the team in white or black
      • Ps' were told to keep a silent mental count of the total number of passes (easy) or silent mental counts of the number of bounce passes and aerial passes (hard). Afterwards they were immediately told to write their answers down on paper
      • They were then asked Did you notice anything unusual?/Did you notice anything other than the six players?/Did you see a gorilla/woman walk across the screen? If they said yes, ps' were asked to provide details of what they noticed. If at any point a ps mentioned the unexpected event, the remaining questions were skipped
      • After questioning, ps' were asked if they had previously been in or heard of a similar experiment. If they said yes their data was discarded
      • Ps' were debriefed and videos were played again if asked. The session lasted 5-10 mins
    • Findings
      • Out of 192 ps', 54% noticed the unexpected event and 46% failed to notice it
      • More ps' noticed it in the opaque condition (67%) than the transparent condition (42%)
      • Opaque: 33% failed to notice the event, despite its visibility
      • Difficulty: More ps' noticed the unexpected event in the easy (64%) than the hard (45%) condition
      • Difficulty: The task difficulty was greater in the transparent condition (easy 56%, hard 27%) than in the opaque condition (easy 71%, hard 62%)
      • The umbrella (65%) was noticed more often than the gorilla (44%)
      • Gorilla: noticed by more ps' who attended to the black team (black 58%, white 27%)
      • Umbrella: There was little difference in noticing the umbrella (black 62%, white 69%)
      • Control condition: 50% noticed the event (roughly the same as those that noticed the opaque/gorilla event (42%))
    • Conclusions
      • Individuals have a sustained inattentional blindness
      • Individuals fail to notice unexpected events if they are engaged in a primary monitoring task. This differs depending on the difficulty
      • Individuals are more likely to notice unexpected events if these events are visually similar to the events they are paying attention to
      • There is no conscious perception without attention


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