5 Perception of Form + Organisation

Question 1

Q: Why is the perception of form and organization important?

Answer 1

A: It’s essential because while the environment presents overlapping objects, our perceptual experience structures them into coherent objects. However, the analogy of the visual system as a camera is flawed because the retina is curved, receptors are unevenly distributed, the image is inverted, tiny, and flat, and the cortical representation does not directly resemble the visual input. Additionally, the visual system must compensate for eye movement, body movement, and changes in the objects being observed, further emphasizing the complexity and importance of perceptual processing.

Question 2

Q: What is Marr’s approach concerned with?

Answer 2

A: Marr’s approach is concerned with representing edges, colors, and areas of contrast change in visual processing.

Question 3

Q: How does Marr’s approach start?

Answer 3

A: Marr’s approach starts with the input to the perceptual system, such as the retinal image, and describes the sequential stages of processing this image.

Question 4

Q: What does each stage of Marr’s approach do?

Answer 4

A: Each stage of Marr’s approach transforms the information from the previous stage into a more complex representation.

Question 5

Q: What are the levels of Marr’s computational model?

Answer 5

A: Marr’s computational model includes three levels: computational theory, algorithmic level, and mechanism level.

Question 6

Q: How does Marr’s model progress in representation?

Answer 6

A: Marr’s model progresses from the primal sketch, representing basic visual features, to the 2.5D sketch, which incorporates depth cues, color, and motion, though it’s not a full 3D representation.

Question 7

Q: What does Marr’s 3D representation involve?

Answer 7

A: Marr’s 3D representation involves analyzing the 2.5D sketch for 3D primitives, producing a representation independent of the observer and leading to conscious experiences of vision.

Question 8

Q: Why is Marr’s approach important?

Answer 8

A: Marr emphasizes understanding the problem to be solved rather than focusing solely on the mechanisms. His approach highlights the importance of function over form in developing algorithms for visual processing.

Question 9

Q: What is the first level of analysis in Marr’s approach?

Answer 9

A: The first level is the retinal image, which captures the intensity of light at each point in the image.

Question 10

Q: What is the second level of analysis in Marr’s approach?

Answer 10

A: The second level is the primal sketch, which represents contrast changes such as blobs, edges, and bars across a range of spatial frequencies.

Question 11

Q: What is the third level of analysis in Marr’s approach?

Answer 11

A: The third level is the 2.5D sketch, which represents orientation, depth, and color relative to the observer.

Question 12

Q: What is the final level of analysis in Marr’s approach?

Answer 12

A: The final level is the 3D representation, which provides a representation of objects in three-dimensional space.

Question 13

Q: What is the Gestalt approach concerned with?

Answer 13

A: The Gestalt approach focuses on the rules of perceptual organization.

Question 14

Q: Is the Gestalt approach a top-down or bottom-up approach?

Answer 14

A: The Gestalt approach is a top-down approach to perception.

Question 15

Q: How does the Gestalt approach view perception of forms and shapes?

Answer 15

A: The Gestalt approach suggests that we don’t see lines and figures individually but perceive forms and shapes as wholes.

Question 16

Q: What aspect of perception is the Gestalt approach interested in?

Answer 16

A: The Gestalt approach is interested in how we group parts of a stimulus together and the way we separate figure from ground.

Question 17

Q: Why is ambiguity rare in our perceptual experience according to the Gestalt approach?

Answer 17

A: Ambiguity is rare in our perceptual experience because the Gestalt approach argues that we see objects according to all their elements taken as a whole, leading to a stable and organized world.

Question 18

Q: What are the Gestalt laws of perceptual organization?

Answer 18

A: The Gestalt laws of perceptual organization include:

Similarity
Good continuation
Proximity
Connectedness
Closure
Common fate
Familiarity
Invariance
Prägnanz, also known as “good figure.”

Question 19

Q: Can you explain the Gestalt law of similarity?

Answer 19

A: Similarity states that similar things appear to be grouped together in perception.

Question 20

Q: What is the Gestalt law of good continuation?

Answer 20

A: Good continuation suggests that points, when connected, result in straight or smoothly curving lines, perceived as belonging together.

Question 21

Q: According to the Gestalt law of proximity, how are things perceived?

Answer 21

A: Proximity suggests that things nearer to each other are grouped together in perception.

Question 22

Q: What’s the law of connnectedness and common fate and familiarity?

Answer 22

things connected are grouped.
fate = same direction + orientation are grouped.
familiar = form groups if meaningful/familiar.

Question 23

Q: What’s the law of closure?

Answer 23

closed figure’s prefferred.

Question 24

Q: What’s the law of invariance

Answer 24

can recognise objects in contorted situations (CAPTCHA)

Question 25

Q: What’s the law of Prägnanz?

Answer 25

central law of Gestalt Psych. Many of the laws are manifestations of Prägnanz.

Question 26

Q: What is figure-ground segregation in visual perception?

Answer 26

A: Figure-ground segregation refers to the process by which our visual system distinguishes between objects of interest (figure) and the background against which they appear (ground).

Question 27

Q: Are there any instances of uncertainty in figure-ground segregation?

Answer 27

A: While figure-ground segregation is usually clear, there are some instances, such as reversible patterns, where uncertainty may arise.

Question 28

Q: What factors influence whether an area is perceived as figure or ground?

Answer 28

A: Several properties influence whether an area is perceived as figure or ground, including symmetry, convexity, area size, orientation, and meaningfulness.

Question 29

Q: How does symmetry affect figure-ground perception?
Q: What role does convexity play in figure-ground perception?
Q: How does area size influence figure-ground perception?
Q: What is the significance of orientation in figure-ground perception?
Q: How does meaning affect figure-ground perception?

Answer 29

A: Symmetrical shapes are usually perceived as figure rather than ground.

A: Convex shapes are typically perceived as figure rather than ground.

A: Smaller stimuli are more likely to be perceived as the figure rather than the ground.

A: Vertical and horizontal orientations tend to be perceived as figure rather than ground.

A: Meaningful objects are more likely to be perceived as figure, suggesting a top-down influence on perception.

Question 30

Q: What are some criticisms of the Gestalt approach to figure-ground perception?

Answer 30

A: Some criticisms include the underplaying of parallel and unconscious processing, inaccuracies in explaining how their laws work, and the descriptive rather than explanatory nature of their laws.

Question 31

Q: What are some positives of the Gestalt approach to figure-ground perception?

Answer 31

A: Positives include the generally correct nature of their laws, the ability to analyze percepts into basic elements, and the recognition that the whole percept is greater than the sum of its parts. Additionally, context and experience play significant roles in perception.

Question 32

Q: What does the bottom-up approach to perception entail?

Answer 32

A: The bottom-up approach starts from the physical stimuli being perceived and then progresses to higher-order cognitive processes. It does not allow higher processes to directly influence processing at lower levels.

Question 33

Q: Can you explain the top-down approach to perception?

Answer 33

A: In the top-down approach, the perceiver builds a cognitive understanding of the stimulus, utilizing sensory information as the foundation but also incorporating other sources of information to construct perception. Higher cognitive processes can influence lower-level processing in this approach.

Question 34

Q: What factors influence the formation and testing of hypotheses during perception?

Answer 34

A: During perception, hypotheses regarding percepts are formed and tested based on sensory information, existing knowledge, cognitive thinking, and expectations.