Deck 3: The Eye and Seeing

Question 1

Electrical impulses carried by neurons are called

A) neural words.
B) neural bits.
C) raw messages.
D) action potentials.

Answer 1

action potentials.

Question 2

The term "receptive field" refers to

A) the patch of retina within which light alters a cell's response.
B) the space occupied by a ganglion cell in the retina.
C) the area outside a donut-shaped composite of ON/OFF regions.
D) none of these

Answer 2

the patch of retina within which light alters a cell's response.

Question 3

Lateral inhibition in vision refers to the fact that

A) when stimulated, rods turn off cones and vice versa.
B) side areas of the visual field are more difficult to see.
C) the "on" and "off" receptive areas of retinal ganglion cells are antagonistic.
D) horizontally oriented stimuli are more difficult to detect than vertically oriented stimuli are.

Answer 3

the "on" and "off" receptive areas of retinal ganglion cells are antagonistic.

Question 4

Stimulation of the ON portion of a ganglion cell's receptive field results in a/an ______ in the neural activity of that cell.

A) decrease
B) increase
C) depends on whether the ON portion is in the center or surround
D) cannot be determined based on the information presented

Question 5

The most common arrangement for the receptive fields of retinal ganglion cells is

A) two vertically adjacent rectangular areas.
B) two concentric circles.
C) two horizontally adjacent squares.
D) diagonally aligned squares.

Question 6

In receptive fields of retinal ganglion cells, the ratio of ON centers to OFF centers is

A) 1:1.
B) 4:1.
C) 1:4.
D) 5:3.

Question 7

Retinal ganglion cells with the smallest receptive field are found in the

A) nasal periphery of the retina.
B) temporal periphery of the retina.
C) superior periphery of the retina.
D) center of the retina.

Question 8

According to the textbook, what kind of a relationship exists between receptive field size and retinal eccentricity?

A) negative
B) positive
C) curvilinear
D) none

Question 9

Some retinal ganglion cells respond only when the receptive field is stimulated by light of a particular color. They are called

A) P cells.
B) Z cells.
C) M cells.
D) Y cells.

Question 10

In which of the following ways do M and P retinal ganglion cells differ?

A) receptive field size
B) relative numbers
C) conduction speed
D) all of these

Question 11

Which one of the following is a trait of P cells?

A) larger than M cells
B) less frequent than M cells
C) larger receptive fields than M cells
D) sensitive to the light of a particular color

Question 12

Which one of the following is NOT a trait of M cells?

A) larger than P cells
B) more frequent than P cells
C) larger receptive fields than P cells
D) respond well to small differences in light levels in center and surround

Question 13

Retinal ganglion cells having their own photopigments are responsible for

A) regulating sleep/wake cycles.
B) setting the general level of adaptation of the eye.
C) adjusting the contrast response of neighboring retinal ganglion cells.
D) conveying information about contrast of contours falling on their receptive fields.

Question 14

If Frank were looking at a figure in which bright and dark regions are perceived within a single stripe, even though there is no variation in the physical distribution of light, he would be looking at

A) the Hermann grid.
B) the Purkinje shift.
C) Mach bands.
D) none of these

Question 15

Bars of light that vary in lightness and yet are invariant in intensity are referred to as

A) Mach bands.
B) lightness constancy.
C) lightness contrast.
D) none of these

Question 16

Which of the following phenomena is/are thought to be due to center-surround antagonism?

A) Mach bands
B) the Hermann grid
C) neither Mach bands nor the Hermann grid
D) both Mach bands and the Hermann grid

Question 17

The property of the surface of an object that governs how much light it reflects is called

A) intensity.
B) lightness.
C) lightness constancy.
D) lightness contrast.

Question 18

The notion that a particular intensity of light can cause various neural response levels is referred to as.

A) constant response.
B) fixed intensity.
C) lightness contrast.
D) lightness constancy.

Question 19

Two objects identical in intensity could appear quite different in lightness under some conditions. This effect is termed

A) lightness contrast.
B) light saturation.
C) the brightness illusion.
D) light blindness.

Question 20

If your perception of lightness is constant despite changes in the amount of light hitting the eye, this is known as

A) constant response.
B) fixed intensity.
C) lightness contrast.
D) lightness constancy.

Question 21

A snowball normally looks white no matter how much total light it is reflecting. This is because of

A) the luminosity of snow.
B) lightness constancy.
C) light convergence.
D) brightness fixation.

Question 22

The amount of light that is reflected by a typical piece of white paper is what percentage of the light that strikes the paper?

A) 10%
B) 30%
C) 50%
D) 80%

Question 23

The ratio of the number of receptors to the number of ganglion cells is referred to as

A) visual acuity.
B) sensitivity.
C) convergence.
D) none of these

Question 24

The average amount of convergence of receptors onto retinal ganglion cells is

A) 10:1.
B) 50:1.
C) 80:1.
D) 125:1.

Question 25

If you had in each eye only one ganglion cell on which all photoreceptors converged, your eye would show

A) high resolution.
B) high sensitivity.
C) robust lateral inhibition.
D) a pronounced Purkinje shift.

Question 26

Increasing the number of receptors that contribute input to a retinal ganglion cell is known as

A) temporal summation.
B) duplex solution.
C) spatial summation.
D) none of these

Question 27

What problem is solved by the "Duplex Solution?"

A) the conflicting demands of sensitivity and resolution
B) the differing light-bending characteristics of the cornea and lens
C) the need to provide nourishment to, and to remove waste products from, the retina
D) Fechner's paradox

Question 28

Seeing in dim light is referred to as

A) scotopic vision.
B) photopic vision.
C) duplex vision.
D) none of these

Question 29

Seeing during daylight is referred to as

A) scotopic vision.
B) photopic vision.
C) duplex vision.
D) none of these

Question 30

Within certain limits, all stimuli having the same product of intensity and area will be equally detectable. This principle is called

A) temporal summation.
B) spatial summation.
C) Bloch's law.
D) Ricco's law.

Question 31

In vision, increased duration of a visual stimulus can be traded off for lower intensity. This is referred to formally as

A) the Helmholtz constant.
B) Ricco's law.
C) Piper's law.
D) Bloch's law.

Question 32

In the fovea, increased area of a visual stimulus can be traded off for lower intensity. This is referred to formally as

A) the Helmholtz constant.
B) Ricco's law.
C) Piper's law.
D) Bloch's law.

Question 33

Which area of the retina has the highest spatial resolution?

A) periphery
B) fovea
C) choroid
D) optic disk

Question 34

Which of the following factors influence(s) visual acuity?

A) spacing of cones
B) level of illumination
C) spacing between adjacent stimuli
D) all of these

Question 35

If you needed an eye that would be particularly effective at low light levels, you should probably choose one that has a high concentration of

A) cones.
B) ganglion cells.
C) rods.
D) photons.

Question 36

The best-known measure of resolution is

A) visual acuity.
B) sensitivity.
C) convergence.
D) none of these

Question 37

What part of the spectrum would you pick to assure that photopic sensitivity was greater than scotopic sensitivity?

A) yellow
B) blue
C) red
D) green

Question 38

As night falls, a red flower seems to fade in brightness compared to its green stem or leaves. This change in vision is called

A) the Purkinje shift.
B) nocturnal transition.
C) Muller's shift.
D) spectral adaptation.

Question 39

To get maximally effective reading light for your money, you should use bulbs that emit light at wavelengths of _____ nanometers.

A) 200
B) 400
C) 550
D) 650

Question 40

Which of the following is the most efficient light source?

A) a tungsten light
B) a fluorescent light
C) sunlight
D) a jar of fireflies

Question 41

To establish the dark-adaptation curve of the rod system alone, you would present the test light

A) at 300 nanometers wavelength.
B) at 700 nanometers wavelength.
C) in the center of the retina.
D) in the periphery of the retina.

Question 42

Night blindness can result from

A) cone impairment.
B) vitamin C deficiency.
C) vitamin A deficiency.
D) too much retinal convergence.

Question 43

What is a receptive field, and how is it measured?

Question 44

Describe two possible perceptual consequences of center/surround antagonism in retinal ganglion cells, and explain how these consequences come about.

Question 45

What is lightness constancy, and why is it important?

Question 46

Describe the relationship between retinal eccentricity and convergence.

Question 47

Under what conditions would you want to have a visual system that emphasized spatial resolution? What would be the costs of this emphasis?

Question 48

Why does the color of objects seem to change during the transition from bright daylight to twilight?

Question 49

Describe dark adaptation and explain its mechanism.