Chapter Questions
What was Ibn alHaytham's evidence that we see only because light enters the eyes, not by sending out sight rays?
If someone electrically stimulated the auditory receptors in your ear, what would you perceive?
If it were possible to flip your entire brain upside down, without breaking any of the connections to sense organs or muscles, what would happen to your perceptions of what you see, hear, and so forth?
What makes the blind spot of the retina blind?
You sometimes find that you can see a faint star on a dark night better if you look slightly to the side of the star instead of straight at it. Why?
If you found a species with a high ratio of cones to rods in its retina, what would you predict about its way of life?
As Figure 5.9 shows, medium-wavelength cones respond most strongly to light that we perceive as green. Long. wavelength cones respond most strongly to light that we perceive as yellow. According to the trichromatic theory, what causes us to perceive yellowish green?
According to the opponent-process theory, under what circumstance would you perceive a white object as blue?
When a television set is off, its screen appears gray. When you watch a program, parts of the screen appear black, even though more light is actually showing on thescreen than when the set was off. What accounts for theblack perception?
Figure 5.9 shows $500 \mathrm{nm}$ light as blue and $550 \mathrm{nm}$ light as yellow. Why should we nevertheless not call them "blue light" and "yellow light"?
Why is color vision deficiency a better term than color blindness?
Where does the optic nerve start and where does it end?
When light strikes a receptor, does the receptor excite or inhibit the bipolar cells? What effect does it have onhorizontal cells? What effect does the horizontal cellhave on bipolar cells?
If light strikes only one receptor, what is the net effect (excitatory or inhibitory) on the nearest bipolar cell that is directly connected to that receptor? What is the effect on bipolar cells to the sides? What causes that effect?
Examine Figure 5.17 . You should see grayish diamonds at the crossroads among the black squares. Explain why.
As we progress from bipolar cells to ganglion cells to later cells in the visual system, are receptive fields ordinarily larger, smaller, or the same size? Why?
What are the differences between the magnocellular and parvocellular systems?
If you were in a darkened room and researchers wanted to "read your mind" just enough to know whether you were having visual fantasies, what could they do?
What is an example of an unconscious response to visual information?
How could a researcher determine whether a given neuron in the visual cortex is simple or complex?
What do cells within a column of the visual cortex have in common?
What is a feature detector?
What is the effect of closing one eye early in life? What is the effect of closing both eyes?
What early experience would cause a kitten or human child to lose stereoscopic depth perception?
What causes astigmatism?
If an infant is born with dense cataracts on both eyes and they are surgically removed years later, how well does the child see at first??
The brain has no specialized areas for perceiving flowers, clothes, or food. For what items does it have specialized areas?
The ability to recognize faces correlates with the strength of connections between which brain areas?
Area V4 is important for color constancy. What is color constancy?
When you move your eyes, why does it not seem as if the world is moving?
Under what circumstance does someone with an intactbrain become motion blind, and what accounts for the motion blindness?