Simons And Chabris (1999) - Inattentional Blindness

• background

  → INATTENTIONAL BLINDESS - occurs when attentions diverted to another object or task and observers often fail to perceive an unexpected object ,, even if it occurs at the point of fixation
• aim

  → to investigate influence of several factors on inattentional blindness

  • one of these was looking at effect of superimposition compared to live events within video recording ,, another was measuring the impact of task difficulty ,, and a third considered whether the unusualness of the unexpected event had an impact on detection rates
• participants

  → there were 228 participants ,, almost all of whom were undergraduate students (the researchers were based at Harvard University)

  → they volunteered either without payment ,, some were given a large candy bar for taking part ,, and others received a single payment for taking part in this and another unrelated study

  → 36 participants' data was discarded so results were used from 192 participants
• method ; 1

  → participants watched a video of 2 teams of players (white vs black team) passing basketballs

  → they were told to watch one of the teams and count the number of passes that they made

  → between 44-48 seconds into the video an '' unexpected event '' occurred - either a woman carrying an umbrella or a person dressed as a gorilla crossed the screen

  → researchers were interested in whether the Ps saw this '' unexpected event ''
• method ; 2

  → there were 4 IVs in this study - and participants only took part in one condition (therefore independent measures)

  • IV 1 - the type of video ; (transport or opaque)
  • IV 2 - the type of event ; (Umbrella-Woman or Gorilla)
  • IV 3 - the difficulty of task ; (Easy or Hard)
  • IV 4 - the team colour to follow ; (Black or White)
• materials ; unexpected events

  → 2 types of unexpected events ,, only 1 was shown in each clips :

  • Umbrella-Woman Condition - tall woman holding an open umbrella crossed scene from left to right
  • Gorilla Condition - shorter woman ,, dressed in a gorilla costume ,, crossed scene from left to right ,, each event lasted 5 seconds
• materials ; video conditions

  → 2 video conditions :

  • Transparent Video - here the black & white team & unexpected event were filmed seperately & then the 3 separate video streams were superimposed on each other ,, in such a way that each character was transparent
  • Opaque Video - after rehearsal to avoid collisions and to make sure the events looked natural ,, all 7 actors (the 2 teams of 3 players ,, & either the umbrella woman // gorilla) were recorded at same time
• procedure

  → was standardised & a team of 21 experimenters gathered data from 228 ppts. ppts were always tested individually & were informed that task would involve watching clip of basketball players & that they should pay attention to either the white/black team & count no of passes of ball between players of team on which they were to focus. the 'easy' task involved asking participants to keep mental note of all passes their team made ,, 'hard' task involved asking ppts to keep seperate mental note of number of aerial & bouncey passes that their team made - were only shown 1/16 video clips
• procedure ; 2

  → after viewing tape ,, participants were asked to immediately record the number of passes on paper & were then asked a number of surprise questions :

  • while you were doing the counting ,, did you notice anything unusual on the video?
  • Did you notice anything other than the six players?
  • Did you see anyone else (besides the 6 players) appear on the video?
  • Did you see a gorilla // woman carrying an umbrella walk across the screen?

  
• results ; 1

  → overall ,, ppts were more likely to notice unexpected event in opaque condition (67%) compared to transparent condition (42%)

  → as expected ,, more ppts noticed unexpected event in 'easy' condition (64%) compared to 'hard' condition (45%)

  → 'umbrella woman' was noticed more often than Gorilla overall (65% VS 44%) regardless of video type

  
• results ; 2

  → gorilla was noticed more by ppts who attended to actions of black team (58%) than white team (27%) ,, it appears that individuals are more likely to notice unexpected events that shares basic visual features with object they're observing ,, however there was little difference between those attending to black (62%) and white team (69%)

  
• conclusions ; 1

  → inattentional blindness occurs more frequently in cases of superimposition as opposed to live action ,, but is still a feature of both

  • 'unexpected event' was noticed more often in opaque/live action condition (67%) than in superimposed/non-live action condition (42%)
• conclusions ; 2

  → degree of inattentional blindness depends on difficulty of primary task ,, & is more likely when primary task is hard

  • more participants noticed the unexpected event in 'easy' condition (64%) than to 'hard' condition (45%)
• conclusions ; 3

  → observers are more likely to notice unexpected events if these are visually similar to events they're paying attention to

  • gorilla was noticed more by participants who attended to actions of Black (58%) to white team (27%)
• conclusions ; 4

  → objects can pass through the spatial area of attentional focus and still not be 'seen' if they're not specifically being attended to

  • overall ,, approx. half of participants (46%) failed to notice the 'unexpected event' regardless of the condition they were in
• evaluation ; strength ~ 1

  → lab experiment ,, lots of controls in place to manage influence of extraneous variables

  • timings for each video were identical across all conditions ,, this standardised approach makes study high in replicability & reliability of results could be tested

  → collected quantitative data in form of 'Yes' or 'No' answers to questions following video clips ,, allows for easy comparisons amongst diff conditions & isn't open to interpretation

  • calculating % of how many noticed unexpected event - we can directly compare visural inattention across no of different conditions
• evaluation ; strength ~ 2

  → study didn't raise any ethical issues ,, participants consent was obtained prior to their participation. distress was kept to a minimum ,, video & questions are unlikely to cause any undue stress participants were fully debriefed at end of experiment ; there were allowed to view the video again
• evaluation ; weakness ~ 1

  → low ecological validity bc ppts completed attention task watching a video ,, within a controlled situation. irl ,, even when we concentrate carefully on tasks requiring our attention there would be a no of other environmental distractions. furthermore ,, task of counting ball passes doesn't itself reflect our typical visual attention tasks
• evaluation ; weakness ~ 2

  → volunteer sampling ,, consisted mainly of undergraduate students ,, may be difficult to generalise beyond sample bc :

  • young people may be more/less vigilant than average person when paying attention. also students may be used to paying attention (e.g. in lectures) & so they may have shown less inattentional blindness than non-students