14. perceptual organization Flashcards

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1
Q

Perceptual organization def?

A

how we make sense of all the stimuli we perceive so we can identify them and understand the world around us

visual system’s process of dealing with complex, overlapping scenes to make object recognition possible

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2
Q

Image clutter?

A

A characteristic of visual scenes in which many objects are scattered in 3-D space, with partial occlusion of various parts of objects by other objects.

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3
Q

Object familiarity?

A

we can recognize (almost instantly) many different types of familiar objects by matching the mental representation of an object in front of us with a representation from our memory

ex. we can recognize our own suitcase, or recognize A general suitcase

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4
Q

Object variety?

A

we have the ability to distinguish between an enormous variety of objects within one category

ex. diff. types of trees

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5
Q

Viewpoint invariance?

A

We can recognize an object from many different viewpoints

Diff. retinal images can be projected by the same object –> we can still recognize them

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6
Q

5 basic steps of perceptual organization? (**NOT necessarily sequential)

A

A. Represent edges
B. Uniform regions bound by edges
C. Divide regions into figure/ground, assign border ownership
D. Group regions with similar properties
–> “figure” –> candidate objects
–> “ground” –> background
E. Fill in missing edges & surfaces

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6
Q

Simplicity meaning?

A
  • simplicity = the number and placement of SHAPES composing an image
  • visual system is highly BIASED to interpret an image in the simplest way it can
  • an image will be perceived as the fewest shapes possible
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7
Q

Assign border ownership meaning? Important for what other step?

A
  • determine what object the border belongs to
  • perception that an edge (border) is “owned” by a particular region of the retinal image
  • important for figure-ground
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8
Q

Edge extraction* meaning?

A
  • edges = abrupt, elongated changes in brightness and/or color
  • The process where the visual system IDENTIFIES / determines the location, orientation, and curvature of edges in the RETINAL IMAGE
    –> NOT edges of individual objects (yet)
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9
Q

Uniform connectedness meaning?

A
  • a characteristic of REGIONS of the retinal image that have approximately uniform properties
  • represented within edges
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10
Q

Figure-ground organization?
What is figure and what is ground?

A
  • figure is more “thing” like, perceived as part of an object
  • ground is perceived as part of background
  • SURROUNDED objects are usually seen as figure
  • figure is often IN FRONT of ground
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11
Q

Factors that contribute to perception of figure-ground?

A
  • depth (in front of the other thing)
  • surrounded-ness
  • symmetry
  • convexity
  • meaningfulness (suggests there is object recognition BEFORE figure-ground identification in this case)
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12
Q

Neural basis for fig/ground? Where?

What 2 images/graphs/studies explain this?

A
  • Cells in V2 respond to info ab border ownership, assignment, and fig-ground
  • single cell recording in monkeys shows cells with preferred orientations that are more sensitive to figures when they’re on one side of the receptive field
  • fMRI in humans (pinwheel experiment) shows V2 cells got fatigued, but showed more activity when the image changed borders
    –> brain perceives the borders differently in V2
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13
Q

Why is V2 important?

A
  • we know info ab fig-ground happens in V2
  • V2 is relatively EARLY in the visual processing stream
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14
Q

Perceptual grouping def?

A
  • The process by which the visual system COMBINES (groups) diff. regions of the retinal image that “go together” based on SIMILAR PROPERTIES.
  • Combining image regions (parts) into wholes
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15
Q

5 principles of perceptual grouping?

A
  1. proximity
  2. similarity
  3. common motion (common fate)
  4. symmetry and parallelism
  5. good continuation
16
Q

Principle of proximity?

A
  • elements that are close together group more easily than elements that are far apart
17
Q

Principle of similarity meaning? Types?

A
  • similar elements / common features tend to group together

types:
- color
- orientation
- shape
- size

(Sorta the same sorta not?)
- symmetry / parallelism
- proximity

18
Q

Principle of common fate (common motion)? Ex?

A
  • things that move together, belong together
  • a target letter that stops on its own is easy to find
  • target letter “hidden” in a group that keeps moving is harder to find
19
Q

WHY do we group things according to common fate? (Neurological basis)

A
  • 2 small light bars “mirror” 1 long/big light bar
    (if same orientation, same direction)
  • there is synchronized neural activity among neurons that are perceiving each part of the big one and each part of the smaller ones
  • no synchronization if objects move in diff. directions
20
Q

Principle of symmetry and parallelism?

A
  • A type of similarity
  • elements that are symmetrical or parallel are usually grouped together
21
Q

Principle of good continuation? Why is it important?

A
  • two edges that would meet if extended are perceived as a single edge that has been partially occluded
  • really helpful for determining what objects are present in a scene
  • if it looks continuous, it probably is
  • most objects we see are partially occluded, in order for our perception of the world to be constant, we need to understand that they stay continuous
22
Q

Perceptual interpolation meaning?

A

The process by which the visual system FILLS IN hidden edges and surfaces in order to represent the entirety of a partially visible object.

23
Q

2 operations of perceptual interpolation?

A
  • Edge completion
  • Surface completion
24
Q

Edge completion* def?

A
  • Filling in (“making up”) contours that aren’t really there
  • Perception of a partially hidden edge as complete
  • you perceive EXPLICIT edges, that you can “see”
25
Q

Illusory contours def? Ex?

A
  • nonexistent, but perceptually real edges perceived as a result of edge completion

ex. two black circles with white cut outs facing each other
–> makes you think there’s a white rectangle between the black circles

26
Q

Surface completion def? Ex?

A
  • Filling in (“making up”) shapes/surfaces that are partially occluded
  • Perception of a partially hidden surface as complete
  • typically perceive the SIMPLEST shape possible

Ex. –> you see “square covering circle”
It could be…
- square covering circle
- square lined up with pac-man
- a really weird shape that’s just covered by square

27
Q

Heuristics def?

A
  • “rules of thumb” based on evolved principles and knowledge of physical REGULARITIES
28
Q

Perceptual inference def?

A

the interpretation of a retinal image using heuristics