Lecture 19: Vision

Question 1

Why should visual cognition be considered a reconstructive process, rather than a veridical replica of what’s physically out there?

Answer 1

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Question 2

Dark adaptation

Answer 2

reason why perception is not veridical; eyes adjusting in the dark; in the same physical environment, but different visual experiences at different stages of dark adaptation –> vision is not a clear window onto reality

Question 3

Motion aftereffects

Answer 3

reason why perception is not veridical; whatever is perceived does not accurately reflect reality; static image, perceived motion –> more generally: visual illusion

Question 4

Moon illusion

Answer 4

the moon looks larger on the horizon than when it’s high in the sky (camera image appears the same)

Question 5

Lightness constancy (and how we are tricked by shadows)

Answer 5

Refers to the fact that, despite changes in the amount of light falling on an object (illumination), the apparent lightness of the object remains unchanged; brightness illusion

Question 6

Face/vase, necker cube, old woman/young-woman ambiguous figures

Answer 6

vision as a reconstructive act –> vision is constructive

one external image, multiple perceptual interpretations = face/vase, necker cube

perceptual interpretations are mutually exclusive and bistable (fluctuate) = young woman/old woman, statue/eskimo

Question 7

Visual completion and the T-junction hypothesis

Answer 7

only see segments, but we rely on assumption that the objects are complete –> T-junction hypothesis = t-junctions (where images “overlap”) indicate occlusion

Question 8

Illusory contours

Answer 8

visual completion type; imagined “boundaries” between one object and other; often created by the perception of “lines” that divide areas of color or texture

Question 9

Impossible objects

Answer 9

objects look sensible in beginning, but then you discover it doesn’t make sense; brain is constantly doing hypothesis testing

Question 10

Size constancy

Answer 10

Perception of an object as the same size regardless of the distance from which it is viewed

Question 11

Correspondence between left and right eyes, left and right visual field, and left and right hemispheres.

Answer 11

right visual field goes to left hemisphere, left visual field goes to right hemisphere

human eyes are front; the two eyes have overlapping visual field –> input from the left eye goes to both left and right hemispheres: nasal side (side closest to nose) goes to right hemisphere and temporal side (far side) goes to left hemisphere –> both eyes are seeing each side of space