Chapter 3 - Perception and Mental Imagery

Question 1

Distal and Proximal Stimuli

Answer 1

outside world (objects) - physical world
what we experience - perceptual world

distal stimulus: actual object
ex: a tree

proximal stimulus: energy from object reaching our senses
ex: pattern of light falling on retina reflected from trees

perceptual system creates representation of what the distal stimulus is based on information in the proximal stimulus

Question 2

Constructive Process

Answer 2

perceptual system must often fill in information

perceptual system uses available information to make best guess about most likely cause of sensory input

sometimes people make different inferences - results in different perceptual experiences

Question 3

Transduction

Answer 3

conversion of proximal stimulus into neural signals

Question 4

Sensation

Answer 4

the detection of sensory signals and beginning of perception

Question 5

Bottom-Up Processing

Answer 5

incoming sensory information

Question 6

Top-Down Processing

Answer 6

knowledge and experience

Question 7

Bottom-Up Information in Vision

Answer 7

transduction & sensory receptors: light falling on retina converted into neural signals

specialized neurons
rods: low light
cones: high light - color

optic nerves carry information out of eyes
right visual field to left hemisphere
left visual field to right hemisphere

eventually reaches primary visual cortex
neurons respond to basic visual features
spatially organzied, more cortex devoted to central vision

Question 8

Predictions

Answer 8

brain uses experiences and context to anticipate or predict

incoming information often ambiguous, experience helps to resolve ambiguity

Question 9

Perceiving Objects

Answer 9

vision begins with mosaic of light falling on each retina

need to be able to parse the visual array into different areas corresponding to different objects

object segmentation: group areas into different objects, edges and contours define boundaries of objects

Question 10

Figure-Ground Observation

Answer 10

boundaries indicate where objects end, boundaries belong to Figure

the Ground appears to continue on behind figure

rules of figure-ground segregation:
enclosure
symmetry
convexity
meaningfulness

Question 11

Occlusion

Answer 11

blocked views of objects

have to recognize objects without complete view and fill in missing information

in order to complete objects behind occlude – must assign edges to surfaces

amodal completion: completing surfaces behind an occluder

boundary extension: remember seeing more that what was actually present

Question 12

Binocular Depth Clues

Answer 12

our two eyes at slightly different positions in space
two eyes see slightly different views of the world

difference gives us information about depth, gives rise to steropsis, impression of depth based on retinal disparity

Question 13

Monocular Depth Clues

Answer 13

cues for depth that we can use with a single eye

linear perspective
texture gradient
relative size
height in particular plane
occlusion

Question 14

Object Constancy

Answer 14

retinal image changes with different viewpoints of object

able to still recognize from these different views

input changes, but we experience the same object

Question 15

Size Constancy

Answer 15

size of retinal image changes with distance

still perceive objects to be same size

Question 16

Color Constancy

Answer 16

visual system takes color/wavelength of light source into account

perceive object as the same color although inputs are different

Question 17

Lightness Constancy

Answer 17

similar to color constancy

visual system takes amount of light into account when judging lightness of a surface

perceive object as the same lightness although different amounts of light are reaching the eyes under different illuminations

Question 18

Object Recognition

Answer 18

low-level (early) vision: analyzing basic visual features (color, orientation, motion)

high-level (visual) vision: combines features into object representations, compares these representations with memory

Question 19

Agnosia

Answer 19

inability to recognize objects by sight

apperceptive agnosia: impairments in early vision, unable to construct coherent object representations, unable to draw objects right in front

associative agnosia: impairments in later vision, can create representations, problems matching that representation to memory

Question 20

Holistic Processing

Answer 20

most everyone has the same facial features

we process faces holistically
relationships between features
relative size of features

Question 21

Face Inversion Effects

Answer 21

inverting faces affects recognition more than objects
inversion disrupts holistic processing

Question 22

Composite Effect

Answer 22

perceiving half a face is more difficult when it appears against a different complementary half

effect is reduced if face halves are offset – disrupting holistic processing

Question 23

Holistic Processing and Fusiform Face Area (FFA)

Answer 23

Gauthier et al. (2000)

used fMRI to compare activity in FFA of car and bird experts
increased FFA activity when car experts viewed cars and bird experts viewed birds

Question 24

Perception and Action: What and Where

Answer 24

separate visual streams/pathways
- what? stream: identifying an object
- where/how stream: identifying the object’s location

Question 25

Mental Imagery

Answer 25

internal representation of items that are not currently being sensed
may be old, new, imaginary

Question 26

Imagery and the Brain

Answer 26

brain activity in response to imagery

evidence: correlational in nature
indicates something is happening

Question 27

Imagery Debate

Answer 27

Kosslyn’s view of imagery is imagery is depictive in nature and uses much of the same “machinery” as perception

imagery: activates these areas in a top-down fashion
perception: initially activates these areas in a bottom-up fashion