Chapter 3-Feature and Pattern Detection

Question 1

Hyper Columns

Answer 1

-Contain all the neurons necessary to process any pattern in the visual field
-Orientation columns include V1 neurons sensitive to the same orientation
-Ocular Dominance shows preference toward one eye

Question 2

Visual Acuity

Answer 2

Smallest detail that we can recognize

Question 3

Visual Angle

Answer 3

Area on retina that an image occupies

Question 4

Cones and visual acuity

Answer 4

Distribution of cones across the retina affects acuity (Acuity decreases with increased distance from fovea)

Question 5

Spatial Frequency

Answer 5

of cycles per degree of visual angle (Dark to light cycles)

Perceptibility of a pattern is a function of spatial frequency and contrast (More sensitive to moderate frequencies)

Question 6

Spatial Frequency Channels

Answer 6

Coarse- Respond to low frequencies
(Identifies object in visual field)
Medium- Respond to moderate frequencies
(Aids in pattern recognition and detecting contours)
Fine- Respond to high frequencies
(Processes fine details and specific examples of objects)

Question 7

Extrastriate Cortex(V2-V5)

Answer 7

V2- Orientation and movement
V3- Complex and Dynamic form
V4- Color processing
V5- Motion perception

Question 8

Processing Streams

Answer 8

Dorsal- “Where” Stream
Ventral- “What” Stream

Question 9

Edge Detection

Answer 9

Most basic feature the visual system has evolved to detect is an edge or contour
-Receptive fields of striate and extrastriate neurons detect boundaries

Question 10

Illusory contours

Answer 10

Illusory contours can be created when features align, giving the appearance of a boundary

Question 11

Modal v. Amodal completion

Answer 11

Modal-Perception of illusory contours, like in the kanizsa figures
Amodal-Perception of complete but occluded objects

Question 12

Lateral inhibition and edge detection

Answer 12

Lateral inhibition allows for the visual system to detect edges

Question 13

Inverse Projection Problem

Answer 13

An image on the retina can be creates by an infinite number of feature combinations from the environment

Question 14

Accidental Viewpoint

Answer 14

Gives perception of an object that is not present

Question 15

Global v. Local level

Answer 15

Local level- Features
Global Level- Features put together to make a unified whole

Question 16

Gestalt Psych

Answer 16

“The whole is greater than the sum of all parts”

Question 17

Law of good continuation

Answer 17

Two elements will be grouped together if they lie on the same contour

Question 18

Law of closure

Answer 18

We tend to form illusory contours to ‘close’ a figure

Question 19

Law of proximity

Answer 19

Items near each other tend to be grouped

Question 20

Law of similarity

Answer 20

Similar looking items tend to be grouped

Question 21

Law of parallelism

Answer 21

Parallel contours likely to belong to the same group

Question 22

Law of symmetry

Answer 22

Symmetrical regions are likely to be grouped

Question 23

Law of common region

Answer 23

Items will be grouped if they appear to be part of the same, larger region

Question 24

Law of connectedness

Answer 24

Items will be grouped if they are connected

Question 25

Law of pragnanz

Answer 25

We perceive patterns in the simplest way possible

Question 26

Perceptual Ambiguity

Answer 26

Addressed by yate's thesis: 1. The visual environment is inherently ambiguous 2. Visual system must select ONE interpretation and stick with it 3.For efficiency, perception is the simplest interpreation

Question 27

Priming

Answer 27

Presentation of something will influence how you respond to something later -Helps overcome perceptual ambiguity

Question 28

Expectancy

Answer 28

Expectancy through regularity does not affect perceptual ambiguity

Question 29

Figure-ground Differentiation

Answer 29

Visual system must determine which part of the visual field is an object and which is the background Affected by: -Surroundedness -Size -Symmetry

Question 30

Template theories

Answer 30

-Mental blueprints are stored in memory -Recognition occurs by matching image to templates -Problems: -Lots of templates necessary -Cannot explain how we recognize occluded/obscured patterns

Question 31

Pandemonium model

Answer 31

-Occurs across several processing stages -Each stage has perceptual committees that determine what features or patterns are present (Bottom-up)

Question 32

Structural Theories

Answer 32

-All objects can have a structural description -Patterns are recognized by processing structural arrangement of parts -Recognition based on assemblage of parts

Question 33

Principle of componential recovery(Biederman)

Answer 33

Corners are critical for recognition

Question 34

Recognition by Components (RBC) Theory

Answer 34

-Proposes geons are basic units of recognition (Geons are 3d pieces) -When we recognize patterns we detect geons and how they are arranged -Geons are viewpoint-invariant (We recognize them at any orientation)