PSYC 3601: Chapter 5 - Vision

Where does light enter the eye?

A. Iris

B. Fovea

C. Iris

D. Pupil

D. Pupil

The rear surface of the eye, known as the _______ is lined with visual receptors

A. Retina

B. Iris

C. Cornea

D. Rear wall

A. Retina

What forms the optic nerve?

A. The optical tract axons

B. Long tubes called vertebrate

C. The cornea and the retina

D. Axons of ganglion cells joined together

D. Axons of ganglion cells joined together

Amacrine Cells

Specialized retinal cells that contact both the bipolar cells and the ganglion cells, and are especially significant in inhibitory interactions within the retina

The optic nerve

Consists of the axons of ganglion cells that band together and exit through the back of the eye and travel to the brain

The fovea

The central focal point in the retina packed tightly with receptors

The periphery of the retina

A place where a greater number of receptors (primarily rods) converge into ganglion and bipolar cells

The difference between foveal and peripheral vision

Rods

The most abundant in the periphery of the eye and respond to faint light (120million per retina)

Cones

The most abundant in and around the fovea (6 million per retina). Essential for color vision and more useful in bright light

Trichromatic theory

Color perception occurs through the relative rates of response by three kinds of cones: short, medium, and long wavelength

Opponent-process theory

Suggests that we perceive color in terms of paired opposites (red and green, blue and yellow, etc.)

Limitations of color vision theories

Color constancy, the ability to recognize color despite changes in lighting, is not easily explained by these theories

Retinex theory

Suggests the cortex compares information from various parts of the retina to determine the brightness and color for each area

Lateral geniculate nucleus

A place in the thalamus that receives impulses from the optic nerve

The primary visual cortex

Receives information from the lateral geniculate nucleus and is the area responsible for the first stage of visual processing

Blindsight

An ability to respond to visual stimuli that they report not seeing

Simple cells

Cells in V1 that respond to line, or gradient, oriented in particular direction

Complex cells

Cells in V1 or V2 that give best response to moving lines of particular orientation

End-stopped cells (hypercomplex cells)

Respond to a bar-shaped pattern of light anywhere in its large receptive field, provided the bar does not extend beyond a certain point

Properties of simple, complex, and end-stopped cells

Early lack of stimulation of one eye may lead to...

Synapses in the visual cortex becoming gradually unresponsive to input from that eye

Early lack of stimulation of both eyes may lead to...

Cortical responses become sluggish but do not cause blindness

True or false: Cortical plasticity is greatest in early life and eventually ends

False, cortical plasticity never ends

Astignitism

Refers to a blurring of vision for lines in one direction caused by an asymmetric curvature of the eyes

What is the long-term consequence of impaired infant vision?

A. Difficulty recognizing objects

B. Unable to tell that components are part of a whole

C. Depression and mild anxiety

D. A and B

D. A and B

The ventral stream

The "what" path that goes through the temporal cortex

The dorsal stream

The "how" path referring to the visual path in the parietal cortex

What can happen if the ventral stream is damaged?

A. Can identify objects but cannot locate them

B. Blindness

C. Can see where objects are but cannot identify them

D. None of the above

C. Can see where objects are but cannot identify them

What can happen if the dorsal stream is damaged?

A. Can identify objects but not know where they are

B. Can see where objects are but cannot identify them

C. Can no longer identify objects when the right eye is covered

D. Partial blindness is one eye

A. Can identify objects but not know where they are

Visual agnosia

The inability to recognize objects despite satisfactory vision caused by damage to the pattern pathway usually in the temporal cortex

Prosopagnosia

The impaired ability to recognize faces that occurs after damage to the fusiform gyrus of the inferior temporal cortex

Motion perception

Involves a variety of brain areas in all four lobes of the cerebral cortex

Motion blindness

The inability to determine the direction, speed and whether objects are moving which is likely caused by damage in area MT

What is the visual "how" path in the parietal cortex that is important for visually guided movements?

A. Dorsal stream

B. Ventral stream

C. Primary visual cortex

D. Secondary visual cortex

A. Dorsal stream

The receptive field of a receptor is called the _______.

A. Point at which the optic nerve exits the retina

B. Axon hillock

C. Point in space from which light strikes the receptor

D. Point where light shines on, and excites, the visual cortex

C. Point in space from which light strikes the receptor

In what order does visual information pass through the cells of the retina?

What happens when you see something?

A. You send out sight rays that strike the object.

B. Light rays reflect off the object and strike your retina.

C. You send out sight rays, and light reflecting off the object strikes your retina.

D. You neither send out sight rays nor receive light rays onto your retina.

B. Light rays reflect off the object and strike your retina.

What is the route from retinal receptors to the brain?

A. Receptors send axons directly to the brain.

B. Receptors connect to bipolars, which connect to ganglion cells, which send axons to the brain.

C. Receptors connect to ganglion cells, which connect to bipolars, which send axons to the brain.

D. Receptors connect to amacrine cells, which send axons to the brain

B. Receptors connect to bipolars, which connect to ganglion cells, which send axons to the brain.

Where does the optic nerve exit from the retina?

A. At the blind spot

B. At the fovea

C. From the edge of the fovea

D. Diffusely from all parts of the retina

A. At the blind spot

Why is vision most acute at the fovea?

A. The fovea is closest to the pupil.

B. The fovea has an equal ratio of cones to rods.

C. The cornea produces the least distortion of light at the fovea.

D. Each receptor in the fovea has a direct line to the brain.

D. Each receptor in the fovea has a direct line to the brain.

Vision in the periphery of the retina has poor sensitivity to detail but great sensitivity to faint light. Why?

A. Toward the periphery, the retina has more midget ganglion cells.

B. Toward the periphery, the retina has more cones and fewer rods.

C. Toward the periphery, the retina has more convergence of input.

D. Toward the periphery, the light falls farther from the blind spot

C. Toward the periphery, the retina has more convergence of input.

Why do some people have greater than average sensitivity to brief, faint, or rapidly changing visual stimuli?

A. They do not have a blind spot in their retina.

B. The blind spot in their retina is smaller than average.

C. They have more axons from the retina to the brain.

D. They have four types of cones instead of three.

C. They have more axons from the retina to the brain.

Suppose you perceive something as red. According to the trichromatic theory, what is the explanation?

A. Light from the object has excited your long-wavelength cones more strongly than your other cones.

B. Light from the object has excited your short-wavelength cones more strongly than your other cones.

C. Ganglion cells that increase response to red and decrease their response to green are firing strongly.

D. The cortex compares activity over all parts of the retina and computes that one area is red.

A. Light from the object has excited your long-wavelength cones more strongly than your other cones.

If you stare at a white circle surrounded by a green background, and then look at a white surface, you perceive a green circle surrounded by a red background. What does this observation imply about the opponent-process theory?

A. We perceive colors based on the pattern of input to the bipolar and ganglion cells of the retina.

B. The mechanisms of color vision vary from one species to another.

C. Opponent-process color perception depends on the visual cortex, not just the cells in the retina.

D. The opponent-process theory is wrong.

C. Opponent-process color perception depends on the visual cortex, not just the cells in the retina.

An object that reflects all wavelengths equally ordinarily appears gray, but it may appear yellow, blue, or any other color, depending on what?

A. Brightness of the light

B. Contrast with surrounding objects

C. The culture in which you grew up

D. The ratio of cones to rods in your retina

B. Contrast with surrounding objects

Color vision deficiency demonstrates which fundamental point about perception?

A. Color is in the brain and not in the light itself.

B. Each sensory system depends on a different part of the cerebral cortex. C. Color perception varies because of cultural influences.

D. Fatiguing a receptor can lead to a negative afterimage

A. Color is in the brain and not in the light itself.

What do horizontal cells in the retina do?

A. They inhibit neighboring receptors.

B. They inhibit bipolar cells.

C. They inhibit ganglion cells.

D. They stimulate ganglion cells

B. They inhibit bipolar cells.

In humans, what crosses to the contralateral hemisphere at the optic chiasm?

A. Half of each optic nerve, the part representing the nasal half of the retina

B. Half of each optic nerve, the part representing the temporal half of the retina

C. Half of each optic nerve, originating from random parts of the retina

D. All of each optic nerve

A. Half of each optic nerve, the part representing the nasal half of the retina

What is the function of lateral inhibition in the retina?

A. To sharpen borders

B. To enhance colors

C. To recognize objects

D. To increase attention

A. To sharpen borders

Suppose light strikes the retina in a circle, surrounded by dark. Which bipolar cells will show the greatest response, and which will show the least?

A. Bipolars connected to receptors in the center of the circle respond the most. Those connected to receptors farthest from the circle respond the least.

B. Bipolars connected to the receptors just outside the circumference of the circle respond most. Those connected to receptors just inside the circumference respond least.

C. Bipolars connected to the receptors just inside the circumference of the circle respond most. Those connected to receptors just outside the circumference respond least.

D. All bipolars within the circle respond equally, and those outside the circle do not respond at all.

C. Bipolars connected to the receptors just inside the circumference of the circle respond most. Those connected to receptors just outside the circumference respond least.

What is the shape of a receptive field of a ganglion cell?

A. Either a bar or an edge, in a fixed position

B. Either a bar or an edge, anywhere within a large area of the retina

C. Either a bar or an edge, with a strong inhibitory field at one end

D. A circle, with a surround that responds in the opposite way

D. A circle, with a surround that responds in the opposite way

What is the shape of a receptive field of a simple cell in the primary visual cortex?

A. Either a bar or an edge, in a fixed position

B. Either a bar or an edge, anywhere within a large area of the retina

C. Either a bar or an edge, with a strong inhibitory field at one end

D. A circle, with a surround that responds in the opposite way

A. Either a bar or an edge, in a fixed position

In contrast to parvocellular neurons, magnocellular neurons are more sensitive to ____.

A. color

B. small details

C. movement

D. the fovea

C. movement

If you were in a darkened room and researchers wanted to know whether you were having visual fantasies (without asking you), they could measure activity in which brain area?

A. The retina

B. The lateral geniculate nucleus of the thalamus

C. The primary visual cortex

D. The parietal cortex

C. The primary visual cortex

In most cases, blindsight apparently depends on what connection?

A. From the thalamus to the temporal cortex

B. From the occipital cortex to the temporal cortex

C. From the thalamus to the frontal cortex

D. From the occipital cortex to the frontal cortex

A. From the thalamus to the temporal cortex

What evidence suggests that certain types of feature detectors operate in the human visual cortex?

A. When you examine Mooney faces, at first you see only meaningless blobs, but with time and effort you start to perceive faces.

B. After you stare at a waterfall or other steadily moving display, you see stationary objects as moving in the opposite direction.

C. An electrode traveling through a section of the cortex may encounter one neuron after another with receptive fields in the same orientation.

D. Children who are deprived of input in one eye become attentive only to the other eye.

B. After you stare at a waterfall or other steadily moving display, you see stationary objects as moving in the opposite direction.

If a kitten has one eye shut for its first few weeks of life, its visual cortex becomes insensitive to that eye. Why?

A. The receptors die.

B. Any axon that is not used for that long becomes unable to respond.

C. Activity from the active eye inhibits synapses from the inactive eye.

D. The visual cortex becomes responsive to sounds instead of light.

C. Activity from the active eye inhibits synapses from the inactive eye.

What early experience, if any, is necessary to maintain binocular input to the neurons of the visual cortex?

A. Cortical cells will always maintain binocular responsiveness, regardless of their experience.

B. Cortical cells must receive some input to each eye every day.

C. Cortical cells must receive an equal amount of input from the two eyes. D. Cortical cells must usually receive simultaneous input from the two eyes.

D. Cortical cells must usually receive simultaneous input from the two eyes.

If someone is born with dense cataracts on both eyes, and the cataracts are removed years later, what happens?

A. The person remains permanently blind.

B. The person gradually recovers all aspects of vision.

C. The person gains some vision, but remains impaired on object recognition, motion vision, and depth perception.

D. The person gains almost all aspects of vision, but remains greatly impaired on color perception

C. The person gains some vision, but remains impaired on object recognition, motion vision, and depth perception.

The ventral stream of the visual system is specialized for which of these?

A. Identifying locations

B. Coordinating vision with movement

C. Peripheral vision and vision under poor lighting

D. Detailed identification of objects

D. Detailed identification of objects

If someone can identify objects, but does not seem to know where they are, what location of brain damage is likely?

A. Primary visual cortex (V1)

B. Middle temporal cortex (MT or V5)

C. Secondary visual cortex (V2)

D. Parietal cortex

D. Parietal cortex

What is distinctive about visual perception in the inferior temporal cortex?

A. Cells respond only to objects that are symmetrical.

B. Cells respond in proportion to the brightness of light.

C. Cells respond only to objects that are moving at a particular speed.

D. Cells respond to an object regardless of the angle of view

D. Cells respond to an object regardless of the angle of view

The fusiform gyrus is specialized for which of the following?

A. Recognizing faces and other highly familiar objects

B. Maintaining color recognition despite changes in room lighting

C. Identifying the direction and speed of a visual object

D. Coordinating vision with hearing and other senses

A. Recognizing faces and other highly familiar objects

If someone has trouble recognizing faces, what pathway in the nervous system is probably deficient?

A. Connections between the primary visual cortex and area MT (V5)

B. Connections between the fusiform gyrus and part of the occipital cortex C. Connections between the temporal cortex and the parietal cortex

D. Connections between the occipital cortex and the primary motor cortex

B. Connections between the fusiform gyrus and part of the occipital cortex

What happens after damage limited to area MT?

A. Motion blindness

B. Face blindness

C. Color blindness

D. Night blindness

A. Motion blindness

Why is it difficult to watch your own eyes move when looking in the mirror?

A. The eye movements are too fast to see.

B. The eye movements are too small to see.

C. During a saccadic eye movement, the eyes do not move relative to the background of the rest of the face.

D. During saccadic eye movements, activity decreases in area MT.

D. During saccadic eye movements, activity decreases in area MT.