5-Form Perception

Question 1

Gestalt Principles

of visual processing

Answer 1

1. Figure-Ground: distinguish objects from their background
2. Proximity: elements that are close together tend to belong together
3. Closure: tendency to fill in gaps to percieve a whole object
4. Similarity: tendency to group similar objects
5. Continuity: interpret forms in the simplest possible way
6. Common Fate: group elements that change in the same way

see figure 5.1 for examples

Question 2

Bottom-up processing

Answer 2

object recognition is guided by individual features we percieve

Question 3

Top-down processing

Answer 3

object recognition is guided by beliefs or expectations

Question 4

study recorded reading time of participants after priming with related or unrelated words

describe methods and results

Answer 4

flashed a word like “animal” followed by a related word (dog) or unrelated word (log)

• participants read the related word faster
• shows that our expectations can affect our reaction time and perception

Question 5

Geon theory

description + key problem

Answer 5

we have 36 different geons (simple geometric forms) in our memory which we use for object recognition

(eg: ice cream cone = cone + sphere)

largely disproved as certain brain injuries can lead to recognition of some objects (eg: tools) and not others (eg: fruits) even though they are both made up of ‘geons’

Question 6

Template theory

description + key problem

Answer 6

we compare objects to templates in memory
- if an object does not exactly match a template, it is stored as a new object

not enough storage in the brain for every template (eg: we can still recognize faces despite not having seen them at every angle)

Question 7

Prototype theory

description

Answer 7

we compare objects to our ideal prototype

Question 8

Perceptual Constancy

description + example

Answer 8

despite differences in the visual image produced by an object, we can still identify it as unchanging

eg: you understand a dog hasn’t changed colour when a red light is shining on it’s fur

Question 9

Types of perceptual constancies

list + basic description

Answer 9

1. shape constancy: open vs closed door is still a rectangle
2. location constancy: objects still percieved as stationary even while we’re moving
3. size constancy: objects further away are not smaller
4. brightness constancy: objects have the same brightness regardless of the shading on them
5. colour constancy: objects do not change colour despite different lighting conditions

Question 10

Müller-Lyer Illusion

description + which constancy it targets

Answer 10

same two lines with inward pointing arrows or outward pointing arrows –> view lines as different lengths

takes advantage of our size constancy perception, we misinterpret the arrows as depth cues

• people without exposure to right angles are less susceptible to this illusion

see image for visual explanation

Question 11

Ames room illusion

description + which constancy it targets

Answer 11

trapezoidal shaped room –> percieved as a rectangular room

takes advantage of size constancy perception

see image for visual explanation

Question 12

Ponzo illusion

description + which constancy it targets

Answer 12

slanted lines around two horizontal lines –> lines percieved as different lengths

manipulates depth cues to trick size constancy

Question 13

What did Hodgkin & Huxley do?

Answer 13

feature detector cell research: recorded electrical activity in the giant axon of squids

Question 14

What are certain neurons in the optic nerve of frogs only responsive to?
Who researched this?

Answer 14

moving black dots - bug detectors

Lettvin et al.

Question 14

Hubel & Wiesel research

description + findings

Answer 14

flashed a line of light onto the retina

neuron firing changed with ___ of line on the retina:
- location
- orientation
- direction of movement
- shape + size

discovered feature detection cells

Question 15

simple cell

in retina, what does it do?

Answer 15

responds maximally to a bar of certain orientation in a particular region of the retina

Question 16

complex cell

in retina, what does it do?

Answer 16

responds maximally to a bar of certain orientation regardless of location

some respond maximally to a specific direction of movement

Question 17

hypercomplex cell

in retina, what does it do?

Answer 17

responds maximally to a bar of particular orientation and direction of movement and length

Question 18

ventral stream

for visual processing, location + purpose

Answer 18

DOWN from occipital to temporal lobe

what stream
- form
- colour

Question 19

dorsal stream

for visual processing, location + purpose

Answer 19

UP from occipital to parietal lobe

where stream
- location
- movement

Question 20

what to the columns vs layers of the temporal cortex respond to? (in terms of visual stimuli)

answer + example

Answer 20

columns: categories of objects
layers: types of objects within a category

eg: column for apples, layer for red apples

Question 21

what type of stimuli do infants prefer?

Answer 21

the most complex stimuli they are able to perceive

see visual example

Question 22

Timeline for infants learning to perceive objects

age + what features they can percieve

Answer 22

when perceiving objects, infants will focus on and attribute the following features to one object:
- 2 weeks: key features (angles, edges…)
- 2 months: wider areas of objects
- 3 months: whole forms + gestalt theory of closure + movement
- 4 months: some perceptual constancy brightness + color + shape + some size constancy
- 5 months: color + texture

Question 23

what type of object do infants prefer? which qualities of this object do they prefer?

Answer 23

prefer faces even at 4 hours of age

prefer attractive faces and mother’s face at 2 months

Question 24

when can infants begin to detect emotions in faces?

Answer 24

around 5 months

Question 25

evidence against infant preference for faces

Answer 25

• infants will fixate on stimuli with equal complexity to faces just as much as real faces
• infants only start to fixate on facial features (eyes + mouth) later in development (2 months)

Question 26

what happened when kittens were kept in a room with only vertical lines?

Answer 26

they did not develop the ability to perceive horizontal lines

Question 27

what happens when 1 month old kittens are kept in the dark for 3-4 days?
what about a week or more?

Answer 27

3-4 days: experience visual degeneration
1 week+: severe and permanent degeneration

Question 28

what happens to the visual development for infants with cataracts?

Answer 28

the longer it takes to remove the cataracts, the worse the childs vision later in life

Question 29

effects of different damage to the occipital lobe

region + effects

Answer 29

Primary visual cortex damage: can only perceive objects in limited field of vision corresponding to undamaged areas
Extrastriate cortex damage: cannot recognize objects despite fully intact field of vision

Question 30

Visual agnosia

types + cause + effects

Answer 30

Object agnosia: unable to identify objects through sight, can identify them through touch

Prosopagnosia: unable to recognize faces, can still tell they are looking at a face, just can’t tell who’s face