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The Invisible surface that Glows chapter 3 *Jane * Patty * Rath*

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Presentation on theme: "The Invisible surface that Glows chapter 3 *Jane * Patty * Rath*"— Presentation transcript:

1 The Invisible surface that Glows chapter 3 *Jane * Patty * Rath*

2 What do you see? An old man’s portrait? Two people on the sidewalk? A dog taking a nap?

3 The idea of constructing objects… Is that taking it too far? Are we constructing our phenomenal experience of the objects… or are we constructing the object itself? Dr. Hoffman “To experience is to construct, in each modality and without exception.”

4 Evidence for construction of visual objects 1) Subjective contours: to create shape and enhance whiteness 2) Subjective surfaces: accent contrast, black and white

5 Questions… Are we constructing the subjective triangles? And suppose we do, then are we just constructing that triangle alone, or even the black ink borders? Idealists say that we create even the black ink we see on our pages.

6 1)You can construct borders without also constructing changes in brightness. 2)Conversely, you can construct changes in brightness without also constructing borders.

7 Rules that didn’t work Symmetry: you create subjective figures only because we innately prefer symmetry Simultaneous brightness contrast: when objects are views surrounded by a contrasting background, the background induces the images brightness. If so, then more black should lead to brighter whites

8 Rule 11 Construct subjective figures that occlude only if there are convex cusps. Cusps= abrupt changes in slope 1)Convex cusps 2)Concave cusps

9 Occlusion… Key: if there are convex cusps, then any subjective figure that you see will appear to occlude. Pacman vs. smooth square smoothed corners of the blobs look like they are pushed up against the corners of the square, not as if the subjective is occluding what’s behind.

10 Mathematical/logical proof of rule 11 1) As we have seen from Chapter 2, rule 7 stated to interpret a T-junction as one rim occluding another. 2) When the object in front becomes invisible, then the T-junction turns into convex cusps. 3) With the T-junction turned convex cusps, the subjective figure would be constructed to occlude.

11 Support ratio… Even though these 2 squares have convex cusps and the same support ratio (which is the ratio of gap length to total length) but the square in the top is not as bright as the bottom.

12 Nonaccidental relations These lines have the same curves so the probability of them being unrelated is low. Therefore we see black objects on white background and vice a versa.

13 Rule 12 If two visual structures have a nonaccidental relation, group them and assign them to a common origin.

14 Rule 13 If 3 or more curves intersect at a common point in an image, interpret them as intersecting at a common point in space.

15 Magic squares According to rule 13, we would see the first 2 squares because they do not have intersecting curves while in the last square they have three intersecting curves.

16 The eye

17 Rods and cones When you see a line, you are actually constructing the line because the rods and cones don’t pick it up as a straight line.

18 Pointillism, Georges Seurat Likewise, millions of dots are used by artist, Seurat, to come up with this masterpiece where we can see lines and objects.

19 Our retina is only one step of the process of our perception. After retina finishes process of an image, it sends the results to a structure in the midbrain called the lateral geniculate nucleus, LGN. Finally, the results arrive at the primary visual cortex, V1. This process of physiology suggests that we do construct lines. Lines are first constructed in the V1. Eye  LGN  V1

20 What causes what? Does the brain cause phenomenal consciousness? Or Does our phenomenal consciousness construct the brain?

21 Stereo vision The stereo vision works because the image at our left eye is slightly different from the image at the right eye. Our visual intelligence uses the small disparities between the left and right eye images, and some trigonometry to construct shapes in 3D.

22 If this table is my construction, then why does everyone else see the same thing? How can we say that we are constructing, when we see the same object? How are we even sure that we do indeed see the same object? Questions…

23 Argument from Consensus Premise: we all see this table. Conclusion: therefore, none of us constructs the table. This is an enthymeme, an argument with a hidden premise

24 Conclusion: therefore, none of us constructs the table The premise of consensus is just false because we all see X and yet we all construct X. We all see the same things because we construct the same things. We all use the same rules of construction. Premise: we all see this table. Premise: if we all see X then none of us constructs X.

25 Granted that we construct everything we all see according to the same rules of construction… What is it that is actually there for all of us to construct (and see) at the same time and place? Questions…

26 If I construct the table that I see, then why can’t I push the table with my fist? Argument from Compliance Premise: I can’t put my fist through this table. Conclusion: Therefore, I don’t construct the table. This is another enthymeme.

27 Argument from compliance Premise: I want to put my fist through this table. Premise: If I construct X, then X complies with my wishes. Premise: I can’t put my fist through this table. Conclusion: Therefore, I don’t construct this table. Because we construct according to rules, we can’t do to them what you wish if what you wish violates the rules of construction.

28 Subjective Necker Cube You construct the cube but you can’t choose which cube you first see.

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