Psych Chapter 4- The visual system

Question 1

What is the human visible spectrum?

Answer 1

Narrow range of wavelengths of light that we respond to.

Question 2

What is the experience of colour dependent on?

Answer 2

Brightness, Hue, Saturation

Question 3

What is our perception of an object’s brightness influenced by?

Answer 3

The intensity of the reflected light that reaches our eyes.

Question 4

What do black objects do vs. white objects in terms of absorbance?

Answer 4

White objects reflect all light and black objects absorb all the light and reflect none.

Question 5

What is saturation?

Answer 5

Refers to the perceived purity of a colour. Colours that are highly saturated appear more vivid to us.

Question 6

What is the sclera?

Answer 6

The white of the eye.

Question 7

What is the iris?

Answer 7

The coloured part of the eye.

Question 8

What are the pigments responsible for iris colour?

Answer 8

Melanin (brown) and lipochrome (yellowish-brown)

Question 9

What does the iris do?

Answer 9

controls how much light enters our eyes.

Question 10

What is the pupil?

Answer 10

Circular hole through which light enters the eye.

Question 11

What is the pupillary reflex?

Answer 11

Response of our eyes to decreased the amount of light allowed into them when walking out into a bright stimulus.

Question 12

When do the pupils dilate?

Answer 12

When we’re trying to process complex information or when we view someone physically attractive (or when you take drugs).

Question 13

What is the cornea?

Answer 13

Curved, transparent layer covering the iris and pupil. Its shape bends incoming light to focus the incoming visual image at the back of the eye.

Question 14

What is the lens?

Answer 14

Also bends light but, unlike the cornea, the lens changes in curvature, allowing us to fine tune the visual image.

Question 15

What is the lens composed of?

Answer 15

Some of the most unusual cells in the body: they’re completely transparent, allowing light to pass through them.

Question 16

What is accomodation?

Answer 16

In this process, the lenses change shape to focus light on the back of the eyes; in this way, they adapt to different perceived distances of objects.

Question 17

What is myopia?

Answer 17

Nearsightedness. Results when images are focused in front of the rear of the eye, due to our cornea being too steep or our eyes being too long. It is the inability to see far objects well with an intact ability to see close objects clearly.

Question 18

What is hyperonia?

Answer 18

Farsightedness. results when the cornea is too flat or our eyes are too short. It is the inability to see near objects well, with an intact ability to see far objects clearly.

Question 19

What is presbyopia?

Answer 19

The loss of flexibility in the lens due to aging.

Question 20

What is the retina.

Answer 20

Technically part of the brain. Thin membrane at the back of the eye.

Question 21

What is the fovea?

Answer 21

central part of the retina and is responsible for acuity, or sharpness of vision.

Question 22

What two types of receptor cells does the retina contain?

Answer 22

Rods: 
- long and narrow
- enables us to see basic shapes and form
- we rely on rods to see in low levels of light
- there are no rods in the fovea
Cones:
- shaped like small cones
- gives us colour vision
- require more light, used when reading

Question 23

What is dark adaptation?

Answer 23

our eyes adjustment to when we enter a dimly lit room, from a bright environment.

Question 24

What are photopigments?

Answer 24

Chemical that change following exposure to light.

Question 25

What is the optic nerve?

Answer 25

contains the axons of ganglion cells, travels from the retina to the rest of the brain.

Question 26

What is the blind spot?

Answer 26

The place where the optic nerve connects to the retina. It is a region of the retina containing no rods and totally devoid of sense receptors.

Question 27

Describe the optic nerve pathway.

Answer 27

The optic nerve travels from the retina to the rest of the brain. After toptic nerves leave both eyes, they come to a fork in the road called the optic chaism.
Half of the axons cross in the optic chiasm and the other half stay on the same side.
Within a short distance, the optic nerves enter the brain, turning into optic tracts.
The optic tracts send most of their axons to the visual part of the thalamus and then to the primary visual cortex.
The remaining axons go to structures in the midbrain, particularly the superior colliculus.

Question 28

What is feature detection?

Answer 28

Ability to use minimal patterns to identify objects.

Question 29

What are feature detector cells?

Answer 29

Simple and complex cells. They detect lines and edges.

Question 30

Where does visual information travel from after V1?

Answer 30

To higher visual areas like V2, along two major routes, one of which travels to the upper parts of the parietal lobe and the other of which travels to the lower part of the temporal lobe.

Question 31

What are Gestalt principles?

Answer 31

Rules governing how we perceive objects as wholes within their overall context.

Question 32

What are the main gestalt principles?

Answer 32

Proximity: objects physically close to each other tend to be perceived as unified wholes.
Similarity: All things being equal, we see objects as compromising a whole much more so than dissimilar objects.
Continuity: We still perceive objects as wholes, even if other objects block part of them.
Closure: when partial visual information is present, our brains fill in what’s missing. (contours)
Symmetry: we perceive objects that are symmetrically arranged as wholes more often than those that aren’t.
Figure-Ground: perceptually, we make an instantaneous decision to focus attention on what we believe to be the central figure, and largely ignore what we believe to be the background.

Question 33

What is a bistable image?

Answer 33

one we can perceive in two ways.

Question 34

Describe face recognition characteristics.

Answer 34

We don’t need an exact picture of a face to recognize it.

The lower part of the temporal lobe responds to faces.

Question 35

What is the region associated with motion perception?

Answer 35

V5, region located along the pathway that leads to the parietal lobe. Neurons in this region will respond to both the direction and the speed of motion.

Question 36

What is the phi phenomenon?

Answer 36

Illusory perception of movement produced by the successive flashing of images.

Question 37

What is trichromatic theory?

Answer 37

Proposes that we base our colour vision on three primary colours. Based on us having three different cones.

Question 38

What is the cause of colour blindness?

Answer 38

Most often due to genetic mutations or brain damage leading to the inability to see all colours.

Question 39

What are monochromats?

Answer 39

have only one type of cone.

Question 40

What are dichromats?

Answer 40

Most colour blind people. Have two types of cones.

Question 41

What is the opponent process theory?

Answer 41

Holds that we perceive colours in terms of three pairs of opponent cells. Red or green, blue or yellow, black or white. Our nervous system uses both trichromatic and opponent processing principles during colour vision but, different neurons rely on one principle more than the other.

Question 42

What are afterimages?

Answer 42

Occur when we’ve stared at one colour for a long time, look away, and often see replica of the same image. Arise from visual cortex’s processing of information from our rods and cones.

Question 43

What is depth perception?

Answer 43

Ability to see spatial relations in three dimensions.

Question 44

What two cues to we use to gauge depth?

Answer 44

Monocular depth cues and binocular depth cues. Mono is one eye, bino is both eyes.

Question 45

What pictorial cues (monocular) help us perceive depth?

Answer 45

relative size: more distant objects look smaller
texture gradient: texture less apparent with greater distance.
interposition: the close object blocks our view of the further one.
linear perspective: the outlines of rooms or buildings converge as distance increases.
height in plane: distant objects seem to appear higher.
light and shadow: objects cast shadows that give us a sense of their 3D form.

Question 46

What are pictorial cues?

Answer 46

give us a sense of what’s located where in stationary scenes.

Question 47

What is motion parallax?

Answer 47

Ability to judge the distance of moving objects from their speed.
Nearby objects seem to move faster than those far away travelling at the same speed. Also works when we are moving.

Question 48

What is binocular disparity?

Answer 48

Our left and right eyes transmit different information for near objects but see distant objects similarly.

Question 49

What is binocular convergence?

Answer 49

When we look at nearby objects, we focus on the relexively by using our eye muscles to turn our eyes inward.

Question 50

What is blindness?

Answer 50

Dramatic reduction in the ability to see.

Question 51

What is motion blindness?

Answer 51

Patients can’t seamlessly string still images processed by their brains into the perception of ongoing motion.

Question 52

What is visual agnosia?

Answer 52

Deficit in perceiving objects. A person with this condition can tell us the shape of an object but can’t recognize or name it.

Question 53

What is blindsight?

Answer 53

Remarkable phenomenon in which blind people who’ve experienced damage to a specific area of their cortex can still make correct guesses about the visual appearance of things around them. Coarser visual information still reaches the visual information cortex through an alternative pathway and bypasses V1.