Chapter 3: Visual Perception

Question 1

Cornea

Answer 1

Transparent tissue at the front of each eye, plays a key role in focusing incoming light

Question 2

Lens

Answer 2

Works with cornea, muscles control the degree of curvature of the lens, allowing a sharp image to appear on the retina

Question 3

Retina

Answer 3

Light-sensitive tissue that lines the back of the eyeball

Question 4

Photoreceptors

Answer 4

Cells on retina that are sensitive to light and that respond when stimulated by light

Question 5

Rods

Answer 5

Type of photoreceptors, sensitive to very low light levels but that are unable to discriminate hues and have poor acuity

Question 6

Cones

Answer 6

Photoreceptors that are able to discriminate hues and have high acuity, concentrated in the retina’s fovea and become less frequent in visual periphery

Question 7

Acuity

Answer 7

Ability to see fine detail

Question 8

Fovea

Answer 8

Center of the retina, region of best acuity, looking at an object involves lining it up with the fovea

Question 9

Bipolar cells

Answer 9

Type of neuron in the eye, receive input from photoreceptors and transmit output to the retinal ganglion cells

Question 10

Ganglion cells

Answer 10

Type of neuron in the eye, receive input from bipolar cells and the axons of ganglion cells gather to form the optic nerve, carrying info back to LGN

Question 11

Optic nerve

Answer 11

Bundle of nerve fibers, formed from the ganglion cells, carries info from eyes to brain

Question 12

Lateral geniculate nucleus LGN

Answer 12

Located in the thalamus, an important 1st stop for visual information traveling into the brain

Question 13

Lateral inhibition

Answer 13

A pattern in which cells, when stimulated, inhibt the activity of neighboring cells, creating edge enhancement

Question 14

Edge enhancement

Answer 14

Process created by lateral inhibition in which the neurons give exaggerated responses to edges of surfaces

Question 15

Mach bands

Answer 15

An illusion in which one perceives a region to be darker or lighter if its adjacent region is lighter or darker

Think about edge enhancement!

Question 16

Single-cell recording

Answer 16

A technique for recording moment-by-moment activation level of individual neurons

Question 17

Receptive field

Answer 17

Portion of visual field in which a cell within the visual system responds (fires)

Changes in position and orientation will change firing rate

Question 18

Center-surround cells

Answer 18

Type of neuron in the visual system that has a “donut shaped” receptive field

Stimulation of the center has a different impact than the “donut”

Question 19

Area V1

Answer 19

Site on the occipital lobe where axons from the lateral geniculate nucleus first reach the cerebral cortex

This site is the location at which info about the visual world first reaches the brain

Question 20

Parallel processing

Answer 20

System in which many steps are going on at the same time

Contrast with serial processing

Question 21

Serial processing

Answer 21

System in which one step happens at a time in succession with others

Contrast with parallel processing

Question 22

what system

Answer 22

The system of visual circuits and pathways leading from the visual cortex to the temporal lobe and especially involved in object recognition

Question 23

where system

Answer 23

The system of visual circuits and pathways leading from the visual cortex to the parietal lobe and especially involved in the spatial localization of objects and in coordination of movements

Question 24

Binding problem

Answer 24

The problem of reuniting various elements of a scene, given that these elements are initally dealt with by different systems in the brain

Question 25

Neural synchrony

Answer 25

Pattern of *neuron* firing in which neurons in one brain area fire at the same time as neurons in another | Brain uses this pattern to solve the *binding problem*

Question 26

Conjunction errors

Answer 26

Error in perception in which a person correctly perceives what features are present but misperceives how they join together

Question 27

Necker cube

Answer 27

A classic *reversible figure* A 2D drawing that can be perceived as a cube from two different angles

Question 28

Reversible (or ambiguous) figure

Answer 28

Drawings that can be readily perceived in more than one way

Question 29

Figure/ground organization

Answer 29

Processing step in which the perceiver determines which aspects of the stimulus belong to the central object and which aspects belong to the background

Question 30

Gestalt principles

Answer 30

Set of rules that govern how observers organize visual input | Some elements get put together, others are viewed as independent

Question 31

Visual features

Answer 31

The elements of a visual pattern--lines, curves, etc.

Question 32

Perceptual constancy

Answer 32

Achievement of perceiving the constant properties of objects in the world despite changes in the sensory info received | Size, shape, brightness

Question 33

Unconscious inference

Answer 33

Hypothesized steps that perceivers follow in order to take one aspect of the visual scene into account in judging another aspect

Question 34

Distance cues

Answer 34

Info available to the perceiver that allows the perceiver to judge how far off a target object is

Question 35

Binocular disparity

Answer 35

A *distance cue* based on the differences between the two eyes' views of the world | Difference becomes less pronounces as an object moves further from the person

Question 36

Monocular distance cues

Answer 36

Features of the visual stimulus that indicate distance even if the stimulus is only viewed by one eye

Question 36

Pictoral cues

Answer 36

Patterns that can be represented on a flat surface to create the sense of a 3D object or scene

Question 37

Interposition

Answer 37

Monocular distance cue that relies on the fact that objects farther away are blocked from view by closer objects that happen to be in the viewer's line of sight

Question 38

Linear perspective

Answer 38

A cue for distance based on the fact that parallel lines seem to converge as they get farther away from the viewer

Question 39

Motion parallax

Answer 39

A *distance cue* based on the fact that as an observer moves, retinal imgaes of nearby objects move more rapidly than those further away

Question 40

Optic flow

Answer 40

Pattern of change in the retinal image in which the image grows larger as the viewer approaches an object and shrinks as the viewer retreats from it