W5 - Form perception ✅

Question 1

Why is perception of form & organisation important?

Answer 1

Helps with:
- Communication
- Problem-solving
- Memory
- Safety

Question 2

What are 2 approaches to perception of form & organisation?

Answer 2

1. Marr’s approach: concerned with the representation of edges, contours and other areas of contrast change.
2. Gestalt approach: concerned with rules of perceptual organisation.

Question 3

Describe each level of computational model in Marr’s approach?

Answer 3

3 levels of analysis:

1. Computational theory: extracting useful information from the environment
2. Algorithmic level: analyse and process relevant info through a number of steps
3. Implementation level: ‘top-down’ complex processing units

Question 4

What are the stages in Marr’s approach?

Answer 4

1. Retinal Image: raw input
2. Grey level description: light contrast
3. Primal sketch: contrast/boundaries
4. 2(1/2)D sketch: representation of object relative to the observer -> not 3D because doesn’t perceive unseen/overlap parts
5. 3D representation: representation of objects independent of observer

Question 5

What is Gestalt approach to perception of form & organisation?

Answer 5

• Top-Down Approach
• Stimuli grouping/segregation
• 8 principles of perceptual organization
• ‘The whole is greater than the sum of its parts’

Question 6

What are Gestalt laws of perceptual organisation?

Answer 6

1. Similarity
2. Good continuation
3. Proximity
4. Connectedness
5. Closure
6. Common Fate (same direction)
7. Familiarity (meaningful)
8. Invariance (CAPTCHA)

Question 7

What are 5 properties that affect figure-ground segregation?

Answer 7

• Symmetry
• Convexity
• Area
• Orientation
• Meaning/Importance
  -> top-down processing

Question 8

What are the positives & limitations of Gestalt’s approach?

Answer 8

Positives:
- Generally correct
- Perceptions can be analysed into basic elements
- Whole > sum of its parts
- Context and experience affect perception

Limitations:
- Underplay brain’s parallel processing and unconscious processing
- Explanation of how some of their laws worked was wrong.
- Provide a description rather than an explanation.
- Ambiguous & ill defined laws – Prägnanz

Question 9

Limitations of Marr’s approach?

Answer 9

• Downplay the physical limitations of eyes & brain
• Lack of consideration for context in perceptual processes
• Oversimplification of processing