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Sensation + Perception > Chapter 5: Perceiving Objects + Scenes > Flashcards

Chapter 5: Perceiving Objects + Scenes Flashcards

1
Q

What are 5 reasons why it would be difficult to design a machine meant to perceive?

A
  1. Shading and colouring are difficult to interpret (cannot differentiate shadow from pigment)
  2. Objects can be hidden or blurred
  3. Occlusions are common in the environment
  4. Inverse Projection Problem: a specific image on the retina can be caused by an infinite number of objects
  5. Viewpoint Invarience: the ability to recognize an object regardless of the viewpoint
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2
Q

Define Perceptual Organization?

A

Process where elements in the environment become groups to create our perception of objects

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3
Q

What are the 2 theories regarding perceptual organization?

A
  1. Structuralism: perception is created by combining many tiny sensations
  2. Gestalt Psychology: the whole is greater than the sum of its parts
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4
Q

What are 2 pieces of evidence that support the theory of Gestalt Psychology?

A
  1. Apparent Movement (Wertheimer): illusionary phenomenon where if 2 stimuli are flashed close to one another with 50ms in between, movement is perceived from the first stimulus to second
    - Cannot be explained by elementary perception (no movement)
    - Cannot be explained by structuralism theory
  2. Illusory Contours: illusionary contours that represent edges
    (Check notes for drawing)
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5
Q

What are the 5 original Gestalt Principles of Organization?

A
  1. Pragnaz (Law of simplicity): every pattern is seen as the simplest structure possible
  2. Similarity: similar things appear grouped
  3. Good Continuation: lines appear to follow smoothest, continuous path
  4. Proximity: objects that are near appear grouped
  5. Common Fate: elements pointed in the same direction are grouped
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6
Q

What are the 3 newer Gestalt Principles of Organization?

A
  1. Common Region: elements within the same region are grouped
  2. Uniform Connectedness: a connected region (by colour, texture, motion) appears as a single unit
  3. Synchrony: visual events occurring at the same time appear grouped
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7
Q

Define Figure-Ground Segregation

A

Perceiving figures as separate from the background

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8
Q

What are the 5 features of figures and grounds that allow perceptual segregation of the two?

A
  1. Figures are “thing-like” and memorable
  2. Figures are seen in front of the ground
  3. Grounds are “uniformed” and extends behind the figure
  4. The contour separating figure from ground belongs to the figure
  5. In the case of reversible figures, it is not possible to see both simultaneously
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9
Q

What are the 4 factors that influence Figure-Ground Segregation?

A
  1. Location: bottom right likelier to be seen as figure
  2. Convexity: higher convexity likelier to be seen as figure
  3. Size: plus figure/smaller area is seen as figure
  4. Meaning: meaningful region is seen as figure

(Gestalt psychologists did not believe in the influence of experience/exposure)

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10
Q

What is the difference between a scene and objects in a scene?

A

A scene is acted WITHIN, an object is acted UPON

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11
Q

Define Gist

A

A general scene description

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12
Q

What did Potter discover about Gists? Using what experiment?

A

A target photo/description was provided, and observers had to decide if the target photo was showed when provided 16 photos a 250ms each

  • Result: 90% accuracy
  • Finding: it only takes 1/4secs to perceive gists
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13
Q

What did Fei-Fei discover about gists? Using what experiment?

A

Observers were asked to write descriptions of photos that were shown for a range of 20ms-500ms

  • Result: descriptions were more detailed when given more time to view a photo
  • Finding: an overall gist is perceived first, followed by details
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14
Q

What is Masking (used by Fei-Fei)?

A

Presenting unrelated stimulus after presenting the test stimulus

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15
Q

What are Global Features?

A

Features that help get the gist of a scene rapidly

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16
Q

What are the 5 Global Features?

A
  1. Degree of naturalness
  2. Degrees of openness
  3. Degree of roughness
  4. Degree of expansion
  5. Colour
17
Q

Why did the visual system evolve?

A

To take advantage of properties in the environment

18
Q

Define Regularities

A

Characteristics that are correlated with specific objects or locations

19
Q

What is the Oblique Effect?

A

People perceive vertical and horizontal contours more easily, probably because there are more horizontal and vertical lines in our environment (city)

20
Q

Define Semantic Regularities

A

Characteristics associated with the function of scenes

21
Q

What was Hollingworth’s experiment regarding semantic regularities?

A

Observers were asked where a target object was or where they would expect it to be, after being presented with a scene (with or without the target), then the target followed by a blank screen
- Result: both groups accurately predicted

22
Q

What was Palmier’s experiment regarding semantic regularities?

A

A scene and target image are flashed, then observers were asked to identify the object in the target picture

  • Result: when the target fit with context, 80% accuracy
  • Result: when the target felt misplaced, 40% accuracy
23
Q

Define Unconscious Inference

A

Our perceptions are results of unconscious assumptions about the environment

24
Q

Define Heuristic

A

Rule of thumb that provide a best-guess solution to a problem
(Gestalt Principles are heuristics)

25
Q

What is Contextual Modulation?

A

Idea that stimuli utside the receptive field can affect neural firing

  • Neurons in the visual cortex respond the Gestalt Principles (areaV1)
  • Likely due to feedback from higher areas
26
Q

What is the Grill-Spector experiment?

A

FFA was monitored with fMRIs, observers were asked to indicated what they saw when presented either Harrison Ford’s face, a stranger’s face, or texture
- Result: FFA activation was greatest when Ford’s face was correctly identified, least when there was no identification of a face

27
Q

What was Sheinburg+Logotheris’ experiment (using binocular rivalry)?

A

Monkeys were trained to pull levers for sunburst and for butterflies, while neurons in the IT cortex were monitored for response
- Result: vigorous firing for butterflies only

28
Q

What is Binocular Rivalry?

A

A technique used during experiments where 2 separate images are shown to different eyes at the same time; each image can only be seen part of the time

29
Q

What was Tong’s experiment?

A

Binocular rivalry was used when showing participants a house and a face

  • Result: increased activity in parahippocampal place area (PPA) for the house
  • Result: increased activity in FFA for the face
30
Q

What does the Amygdala respond to?

A

Emotional aspects of faces

31
Q

What does the Superior Temporal Sulcus (STS) respond to?

A

Where a person is looking and to mouth movements

32
Q

What does the Frontal Cortex (FC) respond to?

A

While evaluating facial attractiveness

33
Q

Faces elicit fastest eye movements and are processed fastest. When are these heightened?

A
  • When in the right shading, rather inverted colours

- When it is a familiar face

34
Q

What is the Preferential Looking Effect?

A

Preference for familiar faces

Experiment: babies presented 2 identical displays with stimuli displayed, while the amount of time watching each of the screens is recorded

Sensation + Perception (12 decks)

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