L13: Vision 3

Question 1

What did Helmholtz (1821-1894) argue?

Answer 1

inadequate info is received from senses and needs to be augmented by unconcious inference.

Question 2

What did Gregory (1980) argue?

Answer 2

perception is an active process involving internal hypotheses and knowledge

Question 3

Critiques of the constructivist theory of perception

Answer 3

• Fits well with biology
• Does well at explaining “Top Down”
• Does not specify details where perceptual hypotheses are generated
• Under emphasises “Bottom Up”

Question 4

What did Gestalt propose?

Answer 4

law of pragnanz: perception will conform to the simplest explanation of a geometric configuration.

Question 5

5 factors of Gestalt’s theory

Answer 5

proximity, similiarity, good continuation, closure and common fate

Question 6

Critiques of Gestalt’s theory

Answer 6

• principles have proved influential
• combines influence of bottom up with top down perception
• does not explain how grouping happens

Question 7

What are the 3 models of David Marr’s computational theory of vision?

Answer 7

primal sketch, 2 1/2 D model, 3D model

Question 8

What is the primal sketch?

Answer 8

groups edges together into elements

Question 9

What does the 2 1/2 D model do?

Answer 9

add depth

Question 10

What does the 3D model do?

Answer 10

construct a 3D (viewer invariant) object representation

Question 11

What does Biedermans recognition by component theory suggest?

Answer 11

geons are combined and matched together

Question 12

What is a saliemce map?

Answer 12

computational model developed by Itti and Koch

Question 13

What is the aim of salience maps?

Answer 13

determines which part of the image will attract attention

Question 14

Critiques of computational models

Answer 14

• sound basis in neurophysiological evidence
• supported by empirical evidence
• successful practical applications
• lacks explanation of top down factors

Question 15

What did James Gibson study?

Answer 15

Problems experienced by pilots taking off and landing in WWII

Question 16

What did Gibson propose?

Answer 16

• How info was directly extracted form environment
  to guide action
• visual system responds to object action affordances
  which cues actions

Question 17

What did Gibson realise that optic array contained?

Answer 17

• focus of expansion = heading
• texture gradient gives cues to depth and size

Question 18

Critiques of Gibson’s ecological theory of perception

Answer 18

• consistent with contemporary neuroscientific
  evidence
• envrionmental invariants are important in
  computationla models
• denial of need for internal representation
• object affordances has important and
  underappreciated implications

Question 19

What is the top-down approach?

Answer 19

Based upon your observations and prior knowledge and is theory-driven.

Question 20

What is the bottom-up approach?

Answer 20

Based upon the feedback perceived from the world and is data-driven.