Objects and scenes part 1

Question 1

What are the two challenges of object perception? Name them

Answer 1

The inverse projection problem
Viewpoint invariance

Question 2

What is the inverse projection problem

Answer 2

How to we determine the 3D object in the world from the 2D representation on the retina
Different objects can create the same 2D image
Same objects can create different 2D images

Question 3

2 examples of the inverse projection problem

Answer 3

Rock circle
Ambiguous cylinder illusion

Question 4

How does the ambiguous cylinder illusion work?

Answer 4

Blend circle into a square
2 sides arching up and 2 arching down
Looks like square from one angle and circle from the other

Question 5

What is viewpoint invariance

Answer 5

Ability to recognize object regardless of the viewpoint

Question 6

What is the principle of perceptual organization

Answer 6

Gestalt approach

Question 7

What are the three examples we were given for the gestalt approach?

Answer 7

Pacman triangle
Dog
dot woman

Question 8

What is the Gestalt approach and what are some examples?

Answer 8

The whole is other than the sum of its part –> what we perceive is different than just adding up components

Ex: Apparent motion, subjective color, illusory contours

Question 9

What causes us to group elements together according to the gestalt approach?

Answer 9

Principles of perceptual grouping

Question 10

What are the principles of perceptual grouping? (7) just name them

Answer 10

Principle of good continuation
Principle of good figure (simplicity or pragnanz)
Principle of similarity
Principle of proximity
Principle of common fate
Principle of common region
Principle of uniform connectedness

Question 11

What is the principle of good continuation?

Answer 11

Lines tend to follow the smoothest path

Question 12

What is the principle of good figure?

Answer 12

Stimulus patterns are seen so the resulting structure is as simple as possible

ex: olympic sign

Question 13

What is the principle of similarity?

Answer 13

similar things appear grouped together

Question 14

What is the principle of proximity?

Answer 14

Nearby objects appear grouped together

Question 15

What is the principle of common fate?

Answer 15

Elements that move together appear grouped together

Question 16

What is the principle of common region?

Answer 16

Elements that are in the same region of space appear to be grouped together

Question 17

What is the principle of uniform connectedness?

Answer 17

A connected region with the same visual properties is perceives as a single unit

Question 18

What causes us to separate elements apart according to the gestalt principle?

Answer 18

Principle of perceputal segregation

Question 19

What is the principle of perceptual segregation?

Answer 19

Figure-ground segregation

Question 20

Describe the properties of figure/ground separation?

Answer 20

Figure is more “thing-like” and memorable than ground
Figure is seen as in front of ground
Ground is more uniform and extends behind figure
Contour (border) separating figure from ground belong to figure (border ownership)

Question 21

Example of figure ground separation

Answer 21

Rubin’s reversible face-vase
Can only see one at a time

Question 22

What are 2 things that contribute to us seeing figure and ground?

Answer 22

Areas lower in figure are perceived as the figure
Convex shapes are seen as figure

Question 23

What are the 2 characteristics of the gestalt approach

Answer 23

Holistic and Bottom up

Question 24

What does it mean that the gestalt approach is holistic?

Answer 24

Characterized by comprehension of the parts of something as intimately interconnected and explicable only by reference to the whole

Question 25

What does it mean that something is bottom up?

Answer 25

Relying primarily on the stimulus and not on past experience

Question 26

What is the theory of how we group things together that relies on bottom up processing?

Answer 26

Recognition-by-components theory (RBC)

Question 27

What is the recognition by components theory?

Answer 27

We perceive objects by perceiving elementary features and putting them together Uses geons: three-dimentional volumes

Question 28

When do we recognize objects according to RBC theory?

Answer 28

hen enough information is available to identify its geons

Question 29

How is the RBC theory different than gestalt

Answer 29

more specific and quantitative

Question 30

How do we determine the geons (4 characteristics)?

Answer 30

Discriminability Resistance to visual noise Distinctiveness Invariance

Question 31

What is discriminability?

Answer 31

Geons can be distinguished from other geons from almost all viewpoints

Question 32

What is resistance to visual noise?

Answer 32

Geons can be percieved even if it is partially blocked

Question 33

What is invariance?

Answer 33

Recongize no matter the surface markings, illumination direction, and texture

Question 34

What is distinctiveness?

Answer 34

36 different geons have beeen identified

Question 35

How do we recognize objects using geons?

Answer 35

By recognizing geons and their relationship --> relationships matter because 2 objects can have the same geons but be different

Question 36

What does the RBC theory work well for?

Answer 36

Man made objects

Question 37

Do we need all the geons to recognize an object? Give an example?

Answer 37

We can recognize an object from a subset of geons Is an airplane is made of 9 geons we can still identify it very well with 6 geons (96%) and 3 geons (78%) Low error rate

Question 38

What is a principle related to geon recognition

Answer 38

Principle of componential recovery

Question 39

What is the principle of componential recovery?

Answer 39

Key to object recognition is not the amount of information, but the ability to indentify components (geons)

Question 40

What is an example of componential recovery?

Answer 40

You have more error rates when you can't see geons even if the amount of information available is identical

Question 41

What is the neural network model of RBC and what are its characteristics?

Answer 41

JIM (jim and Irv's model) Neurally inspired Multi-layered --> deep Purely bottom up --> no recurrent connections Builds up from small details to overall object

Question 42

What does the first layer of JIM represent? What area does this?

Answer 42

Edges V1 recognizes lines and ends

Question 43

What does the second layer of JIM represent?

Answer 43

vertices, blobs, and axes

Question 44

What are vertices?

Answer 44

Connected paths like an arrow or a Y

Question 45

What happens higher up in the JIM layers?

Answer 45

Determine how pieces relate to eachother and determine geons Single node at the top activates for a single object

Question 46

What are the nodes at the top of JIM?

Answer 46

Nodes that activate for a single object