Week 1 Lecture 1 - theories of visual perception

Question 1

What is Gibson’s theory of perception?

Answer 1

• bottom up approach
• perception is direct
• rich info received sufficient for interaction with env.
• complex cognitive processes are unnecessary

Question 2

How did Gibson study perception?

Answer 2

• study in natural env, not in the lab

Question 3

What did Gibson believe about movement?

Answer 3

as soon as there is movement there’s far more info in the visual display

Question 4

What is the ambient optic array?

Answer 4

• movement gives more info in optic array (visual field)
• structure of light reflected by textured surfaces
• changes due to observer movement

Question 5

What theory are invariants a part of?

Answer 5

Gibson’s

Question 6

What are invariants?

Answer 6

• unambiguous info about env.
• can be directly perceived
• proportion of object above horizon is consistent but changes in distance but not in size
• changes in texture in the optic array tell us about distance, orientation and curvature of surfaces

Question 7

What empirical support is there for Gibson?

Answer 7

ppts could correctly identify object, state their colour and identify the lighting conditions and the objects spatial orientations just from black and white photos of object surfaces

However, overall % of correct answers is actually low when looking at study results

Question 8

What is Gibson’s view of motion?

Answer 8

motion is important and necessary to perceive invariant info
- in a static scene everything is invariant so need to introduce motion to highlight the invariant properties

Question 9

What are the 2 types of motion?

Answer 9

• due to observer movements
• due to object movement

Question 10

What type of movement did Gibson focus on? Why?

Answer 10

• observer movements
• this generates large changes in the ambient optic array

Question 11

What are some practical implications of Gibson’s Optic Flow ideas?

Answer 11

• Horizontal lines are painted on the road, becoming closer together as driver approach junctions
• serve to create the illusion of
  increasing speed, which causes the driver to slow down

Question 12

What theory do affordances relate to?

Answer 12

Gibson’s

Question 13

What are affordances?

Answer 13

• opportunity for action e.g., what the surface/object offers the animal
• believed memory and experience not necessary e.g., affordances occur just by looking at an object

Question 14

What is the constructivist approach to perception?

Answer 14

• retinal image does not provide sufficient info
• perception depends upon stored knowledge

Question 15

Who had a constructivist approach to perception?

Answer 15

Helmholtz

Question 16

What is unconscious inference?

Answer 16

• involuntary, pre-rational and reflex-like mechanism which is a part of the formation of visual impressions

Question 17

What are examples of unconscious inference

Answer 17

• illusions
• naieve optics

Question 18

What is the likelihood principle?

Answer 18

more likely to see an image as 2 separate objects that are overlapping

Question 19

What is the perceptual hypotheses?

Answer 19

• many illusions explained by stored knowledge leading to inaccurate perceptual hypotheses
• e.g., hollow mask illusions explained by our stored knowledge that faces are convex
• also hard wired to see faces –> find faces in inanimate objects (evolutionary basis)