Lecture 2 Flashcards

1
Q

agnosia

A
  • A deficit in recognition despite normal vision
    Observations from patients with agnosia give us an indication of the processing that occurs during vision
    Result from damage to the “what” pathway
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2
Q

apperceptive agnosia

A
  • Patients are unable to name, match or discriminate visually presented objects
    Patients can’t combine basic visual info into a complete percept, therefore they show deficits in copying as well
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3
Q

associative agnosia

A
  • Patients cannot associate a visual pattern with meaning - they can’t recognize what they see
    Patients are able to combine visual features into a whole, so they are able to copy well
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4
Q

steps to visual perception

A
  • Patient data tell us there are separate steps to visual perception
    a. Input/sensation
    b. Basic visual components assembled
    Meaning is linked to visual input
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5
Q

the experience error

A
  • What you see isn’t what you get
    • The false assumption that the structure of the world is directly given from our senses
      Visual illusions illustrate that we don’t always perceive an accurate representation of a visual stimulus
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6
Q

fixation-saccade cycles

A

We have the impression of seeing a continuous image of the world, however, our eyes follow a series of this cycle

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7
Q

fixation

A

When the gaze is directed to a specific object for a brief period of time

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8
Q

saccade

A

When the gaze moves quickly between objects

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9
Q

main difference between approaches to study perception

A

whether the goal of perception is recognition or action

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10
Q

computational approach

A

Concerned with discovering how the brain represents and interprets the distal stimulus (the external object/event in the environment that is being perceived which are located at a distance from the individual)

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11
Q

bottom-up processing

A

○ Data driven
We recognize patterns by analyzing sensory input step-by-step

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12
Q

top-down processing

A

○ Conceptually driven
○ Perception is influenced by our prior knowledge, memories and experiences
○ We use what we know about physical properties of the world to perceive 3D objects from 2D images
We use what we know about how the world is structured to perceive 3D objects from 2D images

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13
Q

arguments against the computational approach

A

§ Analyzing each feature one at a time takes a long time
§ Theories that rely on features cannot explain within category discrimination
Pattern recognition can depend on top-down/conceptually driven effects

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14
Q

template matching

A

According to template theory, we have a mental “stencil” for an array of different patterns

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15
Q

feature matching

A

○ We have a system for analyzing each distinct feature of a visual item
○ Ex. Pandemonium (Selfridge 1959)
Physiological support for feature matching comes from discovery of feature detector neurons in primary visual cortex

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16
Q

biederman’s recognition by components

A

○ Geons are view-point invariant (test objects are processed equally well after having been viewed previously in either the same/different orientation in depth during initial encoding) because they have nonaccidental properties (image properties that are invariant to changes in viewpoint)
But, recognition is impaired when we view objects from non-canonical viewpoints (not part of a set of works that we consider important/good/worth studying)

17
Q

view-based recognition

A

○ Evidence from psychology and physiology does not support a viewpoint invariant approach to object identification
○ Humans appear to have a viewer centered bias
§ Object recognition is faster from familiar viewpoints
Cortical neurons demonstrate viewpoint specificity

18
Q

gestalt approach

A
  • Uses organizational principles to create meaningful perception of the environment
    • Concerned with how perception gets organized into meaningful units
      “The whole is different than the sum of its parts
19
Q

gestalt grouping principles

A

○ Identify characteristics of perception which help determine which components of a stimulus group together
○ We can use these rules to predict what will be perceived based on one law at a time - it is hard to predict the outcome of combining laws
§ Law of proximity
§ Law of similarity
Law of common region

20
Q

role of experience

A

If things have been associated in prior viewings, they will be grouped together in the future

21
Q

perception/action approach

A
  • Assumes the goals of action help determine perception
    • The goal of perception is to provide a perceiver with information about objects’ affordances
    • The environment contains all the information we need for perception
    • The goal of perception is an action
    • Lab experiments using 2D images only study indirect perception
      Unlike Gibson’s view, most modern researchers believe both action and representations are involved in perception, but that action influences how we perceive the world
  • comes from gibson’s direct perception approach
22
Q

gibson’s direct perception approach

A
  • perception/action approach comes from this
    ○ An extreme approach in which affordances (the characteristics or properties of an object that suggest how it can be used) directly connect perception and action without the need for intervening cognitive processes
    § No perceptual representation (no proximal stimulus)
    § No role of memory (no top-down processing)
23
Q

ambient optic array

A

The structure imposed on light by the environment and contains all the information we need for perception

24
Q

motion

A

○ Necessary “pick up” the required information from the optic array
○ Described by optic flow (pattern of apparent motion on the retina caused by the relative motion between an observer and the scene) in the ambient optic array
○ If there is flow in the optic array, the observer is in motion
The direction of flow indicates the direction the observer is moving

25
Q

localization of perception

A
  • Evidence from lesion studies suggest there are 2 anatomical pathways for object recognition
    • Imaging studies have revealed different areas of activation for perception of faces, places, and objects
      Deficits in motion perception and action have been dissociated from object identification
26
Q

ideomotor apraxia

A

Damage to “where” pathway

27
Q

blindsight

A

A result of cortical damage to visual areas and results in a dissociation of visual recognition and vision for action

28
Q

face processing

A
  • Requires more within-category differentiation
    ○ Is this a face -> is this face familiar -> who is this face -> is this face happy or sad -> is this person attractive -> is this person friendly
    Evidence suggests that we process objects and faces differently
29
Q

tanaka and farah 1993

A

Discovered it is a lot easier to recognize parts of houses than parts of faces

30
Q

face inversion effect

A

We are faster and more accurate recognizing upright faces compared to inverted faces

31
Q

is face processing special

A
  • Evidence suggesting we have an innate preference for processing faces and that there are neural areas that process faces
    Some believe it is special (domain specific), others argue there is nothing special about faces other than we are experts at identifying them (general expertise)
32
Q

diamond and carey 1986

A

Suggested dog experts identify dogs in the same way that the rest of us identify faces

33
Q

robbins and mckone 2007

A

Replicated and extended Diamond & Carey’s 1986 study but failed to replicate their findings

34
Q

cambell and tanaka

A

Demonstrated equivalent inversion effects for faces and budgies among budgie experts