Inattentional

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Inattentional
Blindness
Stephanie Fishel Jennifer Pappas Jason Moss Jacob
Hicks Teri Leech
A Failure of the Visual System?
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Objective

• This study attempted to objectively support
  previous claims made about the inattentional
  blindness phenomenon using eye tracking data.
• Inattentional blindness the act of failing to
  perceive clearly visible and salient unexpected
  objects or events in ones environment when
  engaged in a task (Simons Chabris, 1999).
• Example Finding a seat in a crowded movie
  theater.
• Friends may see you enter theater and wave their
  hands.
• You dont sit next to them and they are upset
  because you ignored them.
• However, you did not ignore them.
• You did not perceive them because you were
  actively attending to task of finding an
  available seat in a crowded theater.

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Why Do We Care?
Why Do We Care?

• Processing Control Plant
• Controller attending to display for specific task
  or changes in display.
• Warning alert or icon appears that needs
  immediate attention and controller does not
  notice it and fails to take proper action
• Pilot
• Once again, possible failure to notice warning
  alerts/icons on display

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Background

• Simon and Chabris (1999)
• Asked participants to view a video of two teams
  passing a basketball, one team wearing black and
  the other wearing white and asked the
  participants to count the number of passes made
  between either team
• After approximately 45 seconds, a woman dressed
  in a black gorilla suit walked across the scene.
• Overall, 44 noticed unexpected event of gorilla
• Participants counting the passes made by the
  black team noticed the gorilla significantly more
  often (58) than participants counting passes for
  the white team (27)
• Similarity of the stimulus (the gorilla) to the
  attended objects (the black or the white team)
  effected whether or not the participants noticed
  the event

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Background

• Cater, Chalmers, and Ward (2003)
• Used eye tracking to support the idea that
  inattentional blindness did indeed occur and not
  a degraded use of peripheral vision.
• Showed 2 still images high rendering quality and
  low rendering quality.
• Participants instructed to count of teapots in
  scene.
• Asked if noticed difference in quality between 2
  images.
• 20 unable to differentiate between image
  qualities even when eye tracking data confirmed
  participants fixated on similar objects in scene
  to teapots.
• Therefore inattentional blindness occurred and
  not degraded use of peripheral vision.

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Hypotheses

• This study will attempt to confirm the subjective
  data from previous studies related to
  inattentional blindness, with objective data
  collected through eye tracking
• Hypotheses
• Individuals who see the gorilla will have a
  critical fixation,
• Critical fixation a significantly longer
  fixation in the Region of Interest (ROI)
  indicating detection of the stimulus
• Those who notice the stimulus will have a longer
  total dwell time in the ROI
• Participants counting passes made by the black
  team will be more likely to notice the stimulus
• The critical fixation for the individuals
  counting black team passes will occur sooner than
  those counting white team passes
• The stimulus is more likely to be noticed when
  the distance between it and the attended teams
  basketball is short.

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Equipment

• Tobii 1750 eye-tracker
• Display driven by dual processor xeon Linux
  computer
• System run by a single processor Windows XP
  computer that sends gaze data over a 100 MBit
  network to the Linux computer
• The Tobii eye-tracker calculates gaze positions
  automatically on the Windows computer while the
  Linux computer displays the stimulus
• The Tobii allows head motion of about 30 x 15 x
  20 cm
• Accuracy up to 0.5 degrees and average frame rate
  of 50 Hz

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Experimental Design

• Stimulus
• 31 second video clip originally used in the
  Simons and Chabris (1999) study 5 seconds into
  the clip a woman in gorilla suit walked across
  the screen from right to left paused in the
  middle and beat her chest before walking off the
  screen stimulus of interest present for 10
  seconds
• Participants
• 19 undergraduate students at Clemson University
• 10 males and 9 females
• Mean age 19.42 years (SD 1.43 years)
• Design
• Between-subjects design
• IV color of the team the participant was asked
  to observe
• DVs fixation duration in the ROI, total dwell
  time in the ROI, number of fixations in the ROI,
  and the time to the critical fixation in the ROI.

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Procedure

• Participants completed an informed consent form
• Calibration of the eye tracker
• View the video clip
• Instructed to count the number of passes made by
  either the team wearing white shirts or black
  shirts
• Questionnaire including demographics questions
  and the following
• Which teams passes were you asked to count?
• How many passes did you count?
• While you were counting, did you notice anything
  unusual in the video? If yes, please explain
• Did you notice anything other than the six
  players? If yes, please explain.
• Have you previously participated in an experiment
  similar to this or have you ever heard of such an
  experiment or the general phenomenon?

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Analysis

• Analyzing the Data
• ROI was approximated as a close fitting rectangle
  around the gorilla in each frame
• A hybrid algorithm was used that determined
  saccades based on the weighted sum of a 5-tap
  velocity and a 5-tap acceleration filter.
• The eye events were divided into saccades and
  non-saccadic events
• Computing the Dependent Variables
• Total dwell time in the ROI was computed by
  summing all of the de-noised gaze points
  contained in the ROI
• Total fixation time in the ROI was computed by
  interpolating the starting first and ending
  points over the duration on the event
• An ocular event list was formed of each fixation
  and smooth pursuit along with its start and end
  position, duration, and percent of time in the
  ROI

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Results

• 14 participants were included in the final data
  analysis
• 11 (79) noticed the stimulus and 3 (21) did
  not, X2 4.57, p lt .05.
• Similarity hypothesis 100 (6 out of 6) of the
  individuals assigned to the black team noticed
  the gorilla, whereas only 63 (5 out of 8) of the
  participants assigned to the white team noticed,
  X2 2.86, p .091.
• There were very few true fixations present in the
  data after the analysis.
• For analysis purposes, anything other than a
  saccade
• will be termed a fixation
• 2 x 2 mixed factorial ANOVA ran to test critical
  fixation hypothesis
• Need to see an interaction effect to support
  hypothesis
• No significant interaction found, F(1,12) .779,
  p gt.05.

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Results

• Second similarity hypothesis Because there were
  no observed critical fixations, the hypothesis
  that participants counting the black team passes
  would notice the gorilla sooner than participants
  counting the white team passes was unable to be
  tested.
• Longest fixation in the ROI for participants
  counting the black teams passes occurred
  significantly sooner, at frame 593, than the
  longest fixation for those counting white team,
  at frame 675, t(7) -2.541, p lt .05.
• Total dwell time hypothesis There was no
  significant difference found for total dwell time
  in the ROI between those who noticed and those
  who didnt, t(12) -1.08, p gt .05.
• Proximity hypothesis
• 43.8 of the fixations in the ROI made by
  participants counting white team passes occurred
  when the ball or a white team player is in the
  ROI
• 52.8 of the fixations in the ROI made by the
  participants counting black team passes occurred
  when the ball or a black team player is in the
  ROI

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Results

• 2 participants (18) that noticed the gorilla had
  NO fixations in the ROI
• 2 participants (67) that did NOT notice the
  gorilla, had fixations in the ROI
• Some individuals noticed the gorilla without
  having it cross the fovea, and others do not
  notice the gorilla even when it DID cross the
  fovea.
• Indicates that inattentional blindness is not a
  failure of the visual system, but a failure of
  some cognitive process.

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Results
Scan path for Participant 9, who counted the
white teams passes and did not notice the
stimulus
Scan path for Participant 6, who counted the
black teams passes and did notice the stimulus

• A typical scan path shows only saccades and
  fixations. These scan paths integrate smooth
  pursuits.
• In each picture, the thin magenta lines represent
  saccades. The thicker lines represent smooth
  pursuits. The smooth pursuits start out green
  and change to a more cyan color as they spend
  more time in the ROI.

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Discussion

• Expected to see some individuals (who did NOT see
  the stimulus) with fixations in the ROI but no
  critical fixation.
• Did not expect to have individuals (who DID see
  the stimulus) with no fixations at all in the
  ROI.
• Study lends support to the ideas of other
  researchers that inattentional blindness is a
  failure of the human brain to encode information
  rather than a failure of the visual system.
• Improvements
• More participants!
• Eye tracking, a lot more work with dynamic
  stimuli needs to be done
• Repeat the study with another condition where the
  individuals simply watch the video with no
  previous knowledge of what they are going to see.
  

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Conclusion

• This study marked the first time objective eye
  tracking data was applied to inattentional
  blindness using a well-known dynamic stimulus.
• It provided the first objective evidence that
  inattentional blindness is not simply a result of
  a failure of the visual perception system.
• It was interesting to find such a lack of
  fixations during the presentation of the
  stimulus. Further studies on dynamic stimuli
  should be done to increase eye tracking knowledge
  in this area.

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ANY QUESTIONS?
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References

• Caters, K., Chalmers, A., Ledda, P. (2002).
  Selective quality rendering by exploiting human
  inattentional blindness Looking but not Seeing.
  Proceedings of VRST02, Hong Kong.
• Caters, K., Chalmers, A., Ward, G. (2003).
  Detail to attention Exploiting visual tasks for
  selective rendering. Eurographics Symposium on
  Rendering, Leuven, Belgium.
• 3. Henderson, J.M. Hollingworth, A. (2003).
  Global transsaccadic change blindness during
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• 4. Mack, A. (2003). Inattentional blindness
  Looking without seeing. Current Directions in
  Psychological Science, 12, 180-184.
• 5. Moore, C.M. (2001). Inattentional blindness
  Perception or memory and what does it matter.
  Psyche, 7, NP.
• 6. Most, S.B., Simons, D.J., Scholl, B.J.,
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  of unexpected dynamic events. An
  Interdisciplinary Journal of Research on
  Consciousness, 6(14), NP.
• 7. Most, S.B., Simons, D.J., Scholl, B.J.,
  Jimenez, R., Clifford, E., Chabris, C.F.
  (2001). How not to be seen The contribution of
  similarity and selective ignoring to sustained
  inattentional blindness. Psychological Science,
  12, 9-17.
• 8. Neisser, U. (1979). The control of
  information pickup in selective looking in
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  Eleanor J Gibson Ed. A D Pick (Hillsdale, NJ
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• 9. Neisser, U., Becklen, R. (1975). Selective
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• 10. Newby, E.A., Rock, I. (1998).
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  27, 1025-1040.

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