Object Recognition

Question 1

MIddle Vision

Answer 1

Involves perception of edges and surfaces

determins which regions of an image should be grouped together into objects.

Question 2

Edge Detection

Answer 2

a sudden change in brightness, color, texture- also called a contour

Question 3

Which cells are involved in edge detection?

Answer 3

Cells in V1- tuned to detect edges with different orientations and width.

Question 4

How good is Computer based edge detection

Answer 4

Not as good as humans- sometimes they dont find enough edges or sometimes they find too much

Question 5

What are illusary Contours?

Answer 5

An edge that we perceive that is not actually present.

Question 6

What does middle vision find?

Answer 6

• important edges and ignores others & edges that are not physically present

Question 7

What is Gestalt Grouping?

Answer 7

A set of rules that describe when elements in an image will appear to group together.

Question 8

What are the Gestalt Grouping Rules?

Answer 8

Good continuation
Similarity
Proximity
Parallelism
Symmetry

Common region
Connectedness
Common fate
Synchrony

Question 9

What is good continuation?

Answer 9

a. Elements group to form smoothly continuing lines.

Question 10

What is similarity?

Answer 10

a. Objects that are similar to each other, group together.

Question 11

What is proximity?

Answer 11

a. Objects that are close to each other group together.

Question 12

What is parallelism?

Answer 12

a. Elements that are parallel group together

Question 13

What is Symmetry?

Answer 13

a. Elements that are symmetrical to each other group together.

Question 14

What is Common Region?

Answer 14

a. Elements perceived to be part of a larger region group together.

Question 15

What is Connectedness?

Answer 15

a. Elements that are connected to each other group together.

Question 16

What is common fate?

Answer 16

a. Elements that move in the same direction group together.

Question 17

What is Synchrony?

Answer 17

a. Elements that change at the same time group together.

Question 18

What is a perceptual committee?

Answer 18

Many different and sometimes competing principles are involved in perception.

Question 19

What is the Pandemonium Model?

Answer 19

Developed by Oliver Selfridge (1959).
Perceptual committee made up of “demons”
Demons loosely represent neurons.
Each level is a different brain area.

Question 20

What are ambiguous figures?

Answer 20

A visual stimulus that gives rise to two or more interpretations of its identity or structure.
- Neckar Cube

Question 21

What are the rules of the perceptual committee?

Answer 21

Honor physics and avoid accidents.

Question 22

What is an accidental viewpoint?

Answer 22

A viewing position that produces some regularity in the visual image that is not present in the world.

Question 23

How do the perceptual committees describe accidental viewpoint?

Answer 23

Perceptual committees assume viewpoints are not accidental.

Question 24

What is figure?

Answer 24

a foreground object.

Question 25

What is ground?

Answer 25

the background.

Question 26

What is figure ground assignment?

Answer 26

The process of determining what parts of an image belong to the figure and what parts belong to the ground.

Question 27

What are the gestalt figure ground assignment rules?

Answer 27

Surroundedness A surrounding region is likely to be ground. Size A smaller region is likely to be figure. Symmetry A symmetrical region tends to be seen as figure. Parallelism Regions with parallel edges tend to be seen as figure

Question 28

What is occlusion?

Answer 28

an object blocking another

Question 29

What does relatability have to do with occlusion?

Answer 29

The degree to which two line segments appear to be part of the same contour

Question 30

What is the global superiority effect?

Answer 30

The properties of the whole object take precedence over the properties of parts of the object.

Question 31

What is an non accidental viewpoint?

Answer 31

A feature of an object that is not dependent on the exact (or accidental) viewing position of the observer.

Question 32

What are some nonaccidental features?

Answer 32

- t-junction - y junction - arrow junction

Question 33

What is the template theory?

Answer 33

The proposal that the visual system recognizes objects by matching the neural representation of the image with a stored representation of the same “shape” in the brain.

Question 34

What are some problems with the template theory?

Answer 34

You can recognize an infinite number of different shapes as the same object

Question 35

What is a structural description?

Answer 35

A description of an object in terms of the nature of its constituent parts and the relationships between those parts.

Question 36

What is recognition by components?

Answer 36

Objects are recognized by their parts and how those parts fit together

Question 37

What are geons?

Answer 37

(“geometric ions”): 3-dimensional primitives. Any object can be built out of them.

Question 38

What is viewpoint invariance?

Answer 38

A property of an object that doesn’t change when an observer changes viewpoint.

Question 39

What are some problems with the RBC?

Answer 39

One is that object recognition is not completely viewpoint-invariant.

Question 40

Are there multiple recognition comittees?

Answer 40

Perhaps there are several object recognition processes, depending on the category level. Entry-level category: For an object, the label that comes to mind most quickly. Subordinate-level category: A more specific term for an object. Superordinate-level category: A more general term for an object.

Question 41

What is prosopagnotia?

Answer 41

An inability to recognize faces.

Question 42

What is agnosia?

Answer 42

A failure to recognize objects despite being able to see them.

Question 43

What part of the brain is used in object recognition?

Answer 43

Extrastriate cortex The region of cortex bordering V1. Includes multiple areas involved in visual processing.

Question 44

What is the infertomporal pathway?

Answer 44

Part of the cerebral cortex in the lower portion of the brain. Important for object recognition Part of the “what” pathway

Question 45

What happens when the IT pathway is injured?

Answer 45

leads to agnosia