Chapter 4: Sensation and Perception 4.1-4.3 (Visual)

Question 1

Sensation

Answer 1

simple stimulation of a sense organ; basic registration of light, sound, pressure, odor, taste as parts of your body interact with the physical world

Question 2

Perception

Answer 2

organization, identification, and interpretation of a sensation in order to form a mental representation

Question 3

Transduction

Answer 3

sense receptors convert physical signals from the environment into neural signals that are sent to the CNS

Question 4

Sensory adaptation

Answer 4

sensitivity to prolonged stimulation tends to decline over time as an organism adapts to current (unchanging) conditions

Question 5

Psychophysics

Answer 5

methods that systematically relate the physical characteristics of a stimulus to an observer’s perception

Question 6

Absolute threshold

Answer 6

minimal intensity needed to just barely detect a stimulus in 50% of the trials

Question 7

Sensitivity

Answer 7

how responsive we are to faint stimuli

Question 8

Acuity

Answer 8

how well we can distinguish two very similar stimuli

Question 9

Just noticeable difference (JND)

Answer 9

minimal change in a stimulus that can just barely be detected

Question 10

Weber’s law

Answer 10

for every sense domain, the change in a stimulus that is just noticeable is a constant ratio of the standard stimulus, over a range of standard intensities

Question 11

Signal detection theory (SDT)

Answer 11

way of analyzing data from psychophysics experiments that measure an individual’s perceptual sensitivity while taking noise, expectations, motivations, and goals into account

Question 12

Decision criterion of SDT

Answer 12

(1) strength of the sensory evidence for that stimulus (2) the amount of evidence necessary for your perceptual system to “decide” that the stimulus is present

Question 13

Visual acuity

Answer 13

ability to see fine detail

Question 14

Properties of light waves

Answer 14

Length (hue or what we perceive as color), amplitude (brightness), purity (saturation or richness of color)

Question 15

Accommodation

Answer 15

process by which the eye maintains a clear image on the retina

Question 16

Two types of photoreceptor cells in the retina

Answer 16

Contain light-sensitive proteins that absorb light and transduce it into electrical signals: Cones (color, fine detail, normal daylight) and Rods (night vision, low-light)

Question 17

Fovea

Answer 17

an area of the retina where vision is clearest and there are no rods

Question 18

Blind spot

Answer 18

location in the visual field that produces no sensation on the retina

Question 19

Layers of the retina

Answer 19

photoreceptor cells beneath a layer of transparent neurons called bipolar and retinal ganglion cells

Question 20

Bipolar cells

Answer 20

collect electrical signals from rods and cones and transmit them to the outermost layer of the retina

Question 21

Retinal ganglion cells (RGCs)

Answer 21

they organize the signal from bipolar cells and send them to the brain

Question 22

Lateral geniculate nucleus (LGN)

Answer 22

located in the thalamus of each hemisphere, from where visual signals travel to area V1 at back of the brain

Question 23

Area V1

Answer 23

part of the occipital lobe that contains the primary visual cortex

Question 24

Visible spectrum

Answer 24

rainbow of hues and accompanying wavelengths

Question 25

Types of cones

Answer 25

Sensitive to red (long wavelengths), green (medium wavelengths), blue (short wavelengths) light

Question 26

Color vision deficiency or color blindness

Answer 26

Genetic and sex-linked disorder in which one, two, or all three cone types are missing

Question 27

Color-opponent system

Answer 27

pairs of cone types (channels) work in opposition: L-cone against M-cone, S-cone against M-cone; explains color afterimage

Question 28

Visual receptive field

Answer 28

region of the visual field to which each neuron responds

Question 29

Two visual streams or pathways

Answer 29

Ventral (lower) stream and dorsal (upper) stream; functionally distinct

Question 30

Ventral stream, the "what" pathway

Answer 30

travels across occipital lobe into lower levels of the temporal lobes and includes brain areas that represent an object's shape and identity

Question 31

Dorsal stream, the "perception for action" pathway

Answer 31

travels up from the occipital lobe to the parietal lobes (including some middle and upper levels of temporal lobes) and includes brain areas that identify where an object is and how it's moving

Question 32

Binding problem

Answer 32

how the brain links features together so that we see unified objects in our visual world rather than free-floating or miscombined features

Question 33

Parallel processing

Answer 33

brain's capacity to perform many activities at the same time

Question 34

Illusory conjunction

Answer 34

a perceptual mistake whereby the brain incorrectly combines features from multiple objects e.g. color and shape

Question 35

Feature-integration theory

Answer 35

focused attention is not required to detect the individual features that make up a stimulus but it is required to bind those features together

Question 36

Attention

Answer 36

active and conscious processing of particular information

Question 37

Perceptual constancy

Answer 37

as aspects of sensory signals change, perception remains constant

Question 38

Perceptual contrast

Answer 38

although sensory information from two things may be very similar, we perceive the objects as different

Question 39

Perceptual organization

Answer 39

process of grouping and segregating features to create whole objects organized in meaningful ways

Question 40

Gestalt principles of perceptual grouping

Answer 40

Simplicity, closure, continuity, similarity, proximity, common fate

Question 41

Dimensions in the retinal image

Answer 41

Length and width

Question 42

Monocular depth cues

Answer 42

aspects of a scene that yield information about depth when viewed with only one eye

Question 43

Binocular depth cues (binocular disparity)

Answer 43

the difference in retinal images of the two eyes to provide information about depth; farther object mapped in similar location in the retina

Question 44

Apparent motion

Answer 44

perception of movement as a result of alternating signals appearing in rapid succession in different locations

Question 45

Spacial acuity

Answer 45

ability to distinguish two features that are very close together in space

Question 46

Temporal acuity

Answer 46

ability to distinguish two features that are very close together in time

Question 47

Change blindness

Answer 47

when people fail to detect changes to the visual details of a scene

Question 48

Inattentional blindness

Answer 48

failure to perceive objects that are not the focus of attention

Question 49

Filling-in

Answer 49

our perceptual system uses visual information around the blind spot to fill in area occupied by it

Question 50

Synesthesia

Answer 50

Coupling of two or more senses in around 4% of population

Question 51

Additive color mixing (lights)

Answer 51

Mixing different amounts of visible light waves (primarily red, blue, and green) becomes closer to white as more is added

Question 52

Subtractive color mixing (paints)

Answer 52

Absorbing/subtracting some light wavelengths and reflecting others (primarily cyan, magenta, and yellow) until it becomes black (all absorbed, none reflected)

Question 53

Types of monocular depth cues

Answer 53

linear perspective, texture gradient, interposition, relative size, familiar size, relative height

Question 54

Binocular rivalry

Answer 54

two dissimilar images are presented simultaneously to each eye and perception alternates

Question 55

3D anaglyph images

Answer 55

creating depth perception using binocular disparity

Question 56

Visual-form agnosia

Answer 56

impairment in recognition of visual objects due to damage in lateral occipital cortex (ventral)

Question 57

Mcgurk effect

Answer 57

effect in which conflicting visual and auditory components of a speech stimulus result in illusory percept