Ch 3 Day 2

Question 1

Evidence that perception extrapolates beyond input (sensation)

Answer 1

Reversible/Bistable/Ambiguous figures

Question 2

Why is perception difficult?

Answer 2

• Imput is ambiguous

Ex: The Inverse Projection Problem

-The same object looks

Question 3

Perception and Action

Answer 3

1. Moving around helps us disambiguate objects
2. Constant coordination occurs in the brain as we perceive stimuli while also takin action toward them

Question 4

Serial vs Parallel Processing

Answer 4

Serial Processing
- One step at a time Ex: Reasoning, planning, problem solving
- slow, effortful
- conscious

Parallel Processing
- Many steps at once Ex: Perception
- Fast, easy
-Automatic

Question 5

The “Visual Pathways”

Answer 5

Dorsal -> the “where” pathway: occipital -> parietal

Ventral -> the “what” pathway: occipital -> temporal

Question 6

Optic ataxia

Answer 6

can recognize objects, but can’t grab them

Question 7

Visual Agnosia

Answer 7

can grab objects but can’t recognize them

Question 8

Double dissociation

Question 9

Parallel Processing -> Binding Problem

Answer 9

• Features processed separately
• How are they bound together?

Question 10

Binding Problem

Answer 10

3 Possible Ways to solve the Binding Problem

1. Spatial Position- The visual areas processing features like shape, color, and motion each know the spatial position of the object (receptive field)
2. Neural synchrony- The visual areas processing features of the same object fire in a synchronous rhythm with each other
3. Attention- Focusing attention on an object combines the features (Feature Integration Theory, ch. 4)

Question 11

Theories of Object Perception

Answer 11

1. Helmholtz Theory of Unconscious Inference
2. Environmental Regularities
3. Gestalt Principles

Question 12

Helmholtz Theory of Unconscious Inference (1866)

Answer 12

Likelihood Principle- We perceive the object that is most likely to have caused the pattern of input

Inference- What’s “most likely” is based on past experience

Unconscious- Fast process, we’re not aware
-> Perceptual Constancy

Question 13

Perceptual Constancy

Answer 13

Though images on our retina may vary, we perceive a given object as being the same (constant) in size, shape, or color when we assume that these differences in retinal image are the consequence of distance, viewpoint, or lighting, respectively

Question 14

1. Environmental Regularities

Answer 14

Idea: Perception is turned to common features of the world

Physical Regularity: More horizontal and vortical lines in the world than diagonal (trees, buildings)

Light usually comes from above (The Sun)

Psychological data “Oblique effect”

If we see dark on top and light below, it looks concave. If we see light on top and dark below, it looks convex.

Question 15

Tachistoscope

Answer 15

Pre-computer device to sow stimuli for precise breif duration

Question 16

2. Environmental Regularities

Answer 16

Idea: Perception is tuned to common features of the world

Semantic regularities?

Scene schema- Knowledge of what a kind of scene typically contains. Schemes can guide perception

Question 17

3. Gestalt Principles of perceptual Organization

Answer 17

• How do we figure out what we’re seeing? It starts with grouping sensory input in meaningful ways
• “The whole is greater thant e sum of its parts”

-Visiual elements are automatically grouped together to create larger objects, vased on priniples (rules)

• These processes happen quickly and automatically )=(NOT CONSCIOUS), thought to be bottom-up (not based on experiene)… but?

-Expectations… learned during single lifetime…vs. across evolution

Question 18

Gestalt Principles

Answer 18

tricks/assumptions for perceiving groups of objects

Proximity -Things that are close to each other appear to be grouped together

Similarity- Similar things appear to be grouped together

Connectedness- When lines or other properties connect things, they appear to be grouped together

Common Fate- grouped together move together

Good Continuation- We assume straight or curved continuous lines, rather than lines that abruptly change direction, or line segments that just happen to be aligned

Question 19

4. Bayesian Inference

Question 20

Inverse Projection Problem

Answer 20

3D World -> 2D Image on retina -> 3D mental representation

-Problem: Impossible

Question 21

Resolving Ambiguity: Depth Perception

Answer 21

Binocular disparity: Two eyes but different images… the closer an onjet is

Monocular Cues: Accommodation

-Haze (aerial perspective), elevation, interposition (occlusion), elevation, texture, linear perspective, familiar size

Question 22

Ponzo Illusion!