Topic 1 - Perception

Question 1

Sensation and Perception

Answer 1

• Sensation is receiving input, perception is interpreting
• Sensation is light hitting your eye, perception is seeing the object
• All of your experience of the world, despite seeming direct, are interpretations of sensory input by the brain (“best guesses”)

Question 2

Necker Cube

Answer 2

• You perceive either a cube facing up or down, and can change your interpretation
• Actual image is ambiguous, but our brain guesses

Question 3

Dragon Illusion

Answer 3

• You perceive the dragon turning its head, even though it doesn’t move
• Your brain thinks this makes more sense than the alternative based on previous experience, so it decides that is what is happening

Question 4

Blind Spot

Answer 4

• Eyes have a blind spot where certain things will be obscured from vision
• Our brain tries to pretend the spot isn’t there by filling it in

Question 5

Saccadic Masking

Answer 5

• When your eyes move (a saccade), you temporarily don’t see
• When you move your head, things are blurry because your eyes aren’t “shut off” the same way
• Turns out there’s a significant amount of time where you aren’t actually seeing

Question 6

Cut-off Skull Error

Answer 6

• We tend not to draw the back of the head as big as it actually is
• We have learned that the face is more important, so we kind of ignore the rest
• When drawing, we are trying to give someone visual sensations even though our drawing is already based on our filtered perceptions
• Note that we do perceive the full skull, we just don’t really think about it

Question 7

Concave/Convex dots

Answer 7

• A series of gradient-shaded circles, we perceive the dots with darkness on the bottom as being convex and the dots with darkness on top as being concave
• This is because our brain is used to light shining from above, so we make an assumption based on previous experience

Question 8

Cylinder on Checkerboard

Answer 8

• Two identically shaded grey tiles appear to be different shades because one is in a shadow
• We make an involuntary assumption based on previous experience (ie. that things in shadows are artificially darker)

Question 9

Circle in Clouds

Answer 9

• Circle behind grey clouds appears to be black when on a white background and white when on a black background
• Decision is made based on environmental clue

Question 10

Artists’ Aides

Answer 10

• Use a grid to negate things like cut-off skull error

- Even practiced professionals find it difficult to overcome cognitive biases

Question 11

Dot Walker

Answer 11

• Perceive a small number of moving dots as a person walking
• Perceptive tricks can be helpful in identifying objects, it’s just a problem when it’s not really that object
• Extrapolate very small amounts of information