Chapter 6: The Grand Illusion

• "[S]ome people have concluded that visual experience is all a grand illusion." (78)
• "There are good reasons to question the natural idea that conscious vision consists of a stream of picture-like representations." (81)
  

Filling the Gaps

• "William James noticed ... that when we look around we do not and cannot take in everything at once, and yet we are unaware of having overlooked anything." (81)
• Conceptual filling in: "A car parked behind a tree looks like a whole car, not like two halves separated by a tree trunk; a cat sleeping behind a chair leg looks like a whole cat, not two odd-shaped furry lumps." (81)
• The Blind Spot: "A more controversial kind of filling-in arguably happens at the blind spot."
• The blind spot: "Where the optic nerve enters the back of the eye there are no photoreceptors." (81)
• "In classic demonstrations a small object can be made to disappear from sight by lining it up precisely on the blind spot." (81) [See fig. 6.4 p. 82]
• But what is seen is not a gaping hole but rather "the brain has somehow filled in the gap with gray, or pink, or checks (or ore people in the crowd, or more pebbles on the beach?).  But is this the right conclusion." (82)
• "'[N]o matter how vivid your impression is that you see all that detail [every Marilyn of the wallpaper], the detail is in the world, not in your head.' (Dennett 1991: 355)." (83)
  

Change Blindness

• FIGURE 6.8 (87)
  
• "Change blindness implies that perhaps we do not have a stable and detailed view of the world in consciousness after all, in which case massive integration of successive views [e.g., before & after saccades] is not necessary." (88)
  

Inattentional Blindness

• "Could it be that if you don't pay attention to something, you simply do not see it." (88)
• "Perhaps the most dramatic demonstration of inattentional blindness is in the film Gorillas in our Midst (Simons and Chabris, 1999).  Two teams of students are seen throwing balls to each other and observers are told to watch the white team very carefully and count the number of passes made.  Afterward they are asked whether they saw anything unusual in the film.  What most usually miss is that a woman in a gorilla suit walks right into shot, turns to the camera and thumps her chest, and then walks off to the opposite side." (89)
• "Change blindness can be induced by using 'mudsplashes' appearing at the time of the change." (90)
  

Implications for Theories of Vision

• "What do these results mean?  Clearly they challenge the 'stream of vision' theory ... and imply that vision is not a process of building up rich and detailed inner representations that can be used to compare details from one moment to the next." (90)
• "we began with the idea of a stream of vision and the assumption that it is a stream of internal pictures or representations.  The results on filling-in, inattentional blindness and change blindness all call that idea into question.  (92)