Simons and Chabris

• Background

  Inattentional Blindness -occurs when attention is 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

  Investigate inattentional blindness for complex objects and events in dynamic scenes
• Design

  • Laboratory experiment
  • Independent measures design

  Four Ivs :

  • Type of video (opaque or transparent )
  • Type of event ( Umbrella women or gorilla )
  • Difficulty of task ( Easy or Hard )
  • Team colour to follow ( Black or White )
• Participants

  228 participants - all undergraduate students - volunteered either without incentive or candy bar and others were given a single payment. 26 peoples data discarded so only 192 were used.
• Materials

  Recordings of same actors on same day in the same place. Each video lasted 75 seconds and showed two teams with 3 players either with white or black shirts. They passed a basketball between them in a standard order.
• Between 44-48 seconds the even happened, either:

  • Umbrella women - tall woman with open umbrella
  • Gorilla - shorter woman dressed in gorilla costume

  Two video conditions:

  • Transparent - black team , white team and event filmed separately and superimposed so each character was transparent
  • Opaque - After rehearsal to make sure it looked natural, they were recorded at the same time
• Procedure

  • procedure was scripted so it was standardised and a team of 21 experimenters gathered the data. They were always tested individually and informed what the task was and they should pay attention to either white or black team and count the number of passes they do
• They either had the easy task - keep count of how many passes or hard task - keep count of how many arial and how many bounce passes they made.
• After viewing the tape they were asked number of questions

  1. While you were doing the counting did you notice anything unusual
  2. Did you notice anything other than the 6 players
  3. Did you see anyone else besides the 6 players
  4. Did you see a gorilla/women carrying an umbrella walk across the screen
• If they said yes to any questions they were asked to provide details and if they said yes to having seen a video like this before their data wasn't used. The participants were all debriefed
• RESULTS

  100% of participants noticed the unexpected event in the white, opaque and easy task conditions

  8% of participants noticed the gorilla in the easy, white and transparent condition

  Overall participants more likely to notice unexpected event in the opaque condition (67%) than transparent (42%)

  They noticed it more in the easy condition (64%) than hard (45%)

  Umbrella women noticed more than gorilla - 65% versus 44%

  Individuals more likely to notice something with similar to features as what they're already observing
• Strengths of the procedure

  • controls put in place
  • collects quantitative data
  • didn't really raise any ethical issues
• Limitations of the procedure

  • low ecological validity
  • sample used volunteer sampling and mainly consisted of undergraduate students