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Cognition and language > lecture 8 - concepts and categorisation > Flashcards

lecture 8 - concepts and categorisation Flashcards

1
Q

what is a concept

A

a mental representation useful for cognitive efficacy

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2
Q

what are the two types of concepts

A
  • logical concepts

- natural concepts

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3
Q

what is categorisation

A

the process by which things are placed into groups

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4
Q

why do we categorise

A
  • it reduces complexity of the enviro (cognitive economy)
  • it allows us to recognise novel patterns
  • allows us to establish hierarchy of objects
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5
Q

what is cognitive economy

A

reducing the complexity of the environment

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6
Q

what did roch provide evidence for in the natural categories

A

psychological privelage

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7
Q

what are the 3 levels of the natural categories as a hierachy

A
  • global (subordinate)
  • basic
  • specific (subordinate)
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8
Q

explain the natural category - superordinate level

A
  • highest level of abstraction
  • consists of general categories
  • consists of only a few attributes
  • top level
  • eg birds , furniture
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9
Q

explain the subordinate level of the natural category : as a hierachy

A
  • lowest level of abstraction
  • consists of specific types of objects
  • consists of many attributes
  • eg end of table, songsparrow
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10
Q

explain the basic level of the natural category : as a hierachy

A
  • exists between the 2 extremes subordinate and superordinate
  • is a balance between informativeness and economy (informativeness- of attributes the concept conveys )(economy - the summary of the important attributes)
  • usually acquired first by children
  • recognised more quickly by non experts
  • eg table, sparrow
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11
Q

who usually aquires basic level hierachys first

A

usually first acquired by children

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12
Q

provide some evidence that Evidence that Basic-Level Is Special

A
  • people almost exclusively use basic-lecek names in free naming tasks
  • quicker to identify basic level category as a member of a category
  • children learn basic level quicker than other levels
  • basic level is much more common in adult discourse for superordinate categories
  • different cultures tend to use the same basic level categories - at least for living things
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13
Q

how does basic level hierachys change within cultures

A
  • different cultures tend to use the same basic level categories - at least for living things
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14
Q

what are the two types of characteristics proposed as occurring within a category

A

family resemblance

and

typicality

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15
Q

explain family resemblance characteristic

A

first proposed by Wittgenstein (1953)

is a continuous variable

is a measure of the overlap between members within a category

is measured by the number of shared attributes

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16
Q

how is family resemblance measured

A

is a measure of the overlap between members within a category

is measured by the number of shared attributes

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17
Q

explain typicality

A

refers to the differences in how well members relate to their category (e.g., collie vs. dachshund)

the higher the family resemblance the more typical the item is for common taxonomic categories

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18
Q

what happened in rochs experiment

A
  • pps had to rate a list of words / objects
  • judged on a scale of 1 (good example of a category ) to 7 (poor example)

rated birds and furniture

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19
Q

explain the The Defining-Attribute View to a concept

A

Frege (1952) said a concept can be characterized by a set of defining attributes

intension:
the set of attributes that define what it is to be a member of the concept
bachelor - (male, single, adult)
extension:
the set of entities that are members of the concept
bachelor - (every bachelor)

All of the attributes must be present

Assumes categories are clearly defined and rigid

Defining attributes vs. characteristic attributes

20
Q

what did frege say that the the 2 sets of defining attributes of a concept are

A

intension:
the set of attributes that define what it is to be a member of the concept
bachelor - (male, single, adult)
extension:
the set of entities that are members of the concept
bachelor - (every bachelor)

21
Q

exp;lain the Definitional Approach to Categorization

A

Determine category membership based on whether the object meets the definition of the category

Does not work well

Not all members of everyday categories have the same defining features

22
Q

does the Definitional Approach to Categorization work

A
  • doesnt work well
  • not all members of everyday categories have the same defining features
  • eg chairs - can be a sofa, arm chair, bean bag
23
Q

what is the prototype view

A

Categorization occurs by finding the best prototype/TBC item match

24
Q

what are the different types of prototypes

A
  • average of all members
  • a specific instance of the category
  • a set of characteristic attributes
  • regardless, the prototype is the most typical
25
Q

what is the evidence given for the prototype view

A
  • the typicality gradient is a good predictor of the categorization time
  • the most typical member is usually named first
  • children learn the typical members first
26
Q

what is the Typicality effect of the prototype apporoach

A
  • prototypical objects are processed preferentially
  • prototypical category members are more effected by a priming stimulus
  • roch1975- hearing green primes a highly protoypical green
27
Q

what is the procedure for rochs prototypical experiment

A
  • priming experiment
28
Q

what are the result of rochs experiment

A

Results for the conditions when the test colors were the same are shown on the right. (a) The person’s “green” prototype matches the good green, but (b) is a poor match for the light green.

29
Q

what is the examplar approach

A
  • concept is represented by multiple examples
    (rather than a single prototype)
  • Examples are actual category members (not abstract averages)

To categorize, compare the new item to stored examples

30
Q

how is the examplar approach similar to the prototype view

A
  • both say representing a category is not defining it
31
Q

how does the examplar approach differ to the prototype view

A
  • representation is not abstract
  • descriptions of specific examples
    • The more similar a specific exemplar is to a known category member, the faster it will be categorized
32
Q

what does the examplar approach explain

A

Explains typicality effect
Easily takes into account atypical cases
Easily deals with variable categories

33
Q

what is a semantic network

A

Concepts are arranged in networks that represent the way concepts are organized in the mind

34
Q

what is a node

A

category/concept

35
Q

what does collins and Quilian assume about semantic networks

A
  • nodes= concepts/ categories
  • concepts are linked
  • model for how concepts and properties are associated in the mind
36
Q

how does cognitive economy explain semantic networks

A

Cognitive economy: shared properties are only stored at higher-level nodes

Exceptions are stored at lower nodes

Inheritance
Lower-level items share properties of higher-level items

37
Q

what does the distance between concepts predict

A

: The distance between concepts predicts how long it takes to retrieve information about concepts as measured by the sentence verification technique. Because it is necessary to travel on two links to get from canary to animal (left), but on only one to get from canary to bird (right) it should take longer to verify the statement “a canary is an animal

38
Q

explain Spreading activation

of semantic networks

A
  • activation in the arousal level of the node
  • when a node is activated, activity spreads out along all connected links
  • concepts that receive activation are primed and more easily accessed from memory
39
Q

what are the criticisms of collins and quillians semantic networks

A
  • cant explain typiclaity effects
  • cognitive economy
  • some sentance verification results are problematic for the model
40
Q

what are the strengths and weaknesses of the semantic networks

A
  • Is predictive and explanatory of some results, but not all
  • Generated multiple experiments
  • Lack of falsifiability
  • No rules for determining link length or how long activation will spread
  • Therefore, there is no experiment that would “prove it wrong”
  • Circular reasoning
41
Q

what are the 3 types of neuron like units in the connectionist approach

A

input units : activated activated by stimulation from environment

hidden units: receive input from input units

output units: receive input from hidden units

42
Q

explain the connectionist approach

A

Parallel distributed processing
Knowledge represented in the distributed activity of many units
Weights determine at each connection how strongly an incoming signal will activate the next unit

43
Q

explain how learning occurs in the connectionist approach

A

How learning occurs

Network responds to stimulus

Provided with correct response

Modifies responding to match correct response

44
Q

what is error signal in the connectionist approach

A
  • difference between actual activity of each output unit and the correct activity
45
Q

what is backpropagation the connectionist approach

A

error signal transmitted back through the circuit

indicates how weights should be changed to allow the output signal to match the correct signal

the process repeats until the error signal is zero

46
Q

explain how learning occurs in the connectionist approach

A

Slow learning process that creates a network capable of handling a wide range of inputs

Learning can be generalized

Graceful degradation: disruption of performance occurs gradually as parts of the system are damaged

Cognition and language (21 decks)

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