Semantic organization

1
Semantic organization

• Rosch and others have argued that our
  categorization of the world is not an arbitrary
  historical accident, but reflects our
  psychological makeup, and hence is subject to
  investigation

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Semantic organization

• Berlin Kay (1969) investigated colour names
  across 100 different languages
• order and frequency of colours used is consistent
  across cultures
• black white
• red
• green yellow
• blue
• brown
• purple pink orange grey

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Semantic organization

• I.e. If there are two words for colours they tend
  to be black and white three black, white, and
  red etc.

4
Semantic organization

• Rosch-Heider (1972) experiment with
  American-speaking subjects and members of the
  Dani, a stone-age New Guinea tribe
• Dani only had words for black and white

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Semantic organization

• Rosch built on a study by Brown Lenneberg
• Brown Lenneberg showed that the Zuni, whose
  language categorizes colours different from
  English-speakers, and North American English
  speakers tend to remember focal colours (e.g.,
  pure green) better than nonfocal (e.g., purple)
• Focal colours are colours that are selected to be
  good exemplars of particular colours

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Semantic organization

• Experiment 1.
• showed a single coloured chip, and were required
  to recognize it from a set of 160 chips
• both U.S. and Dani subjects performed better with
  focal colours

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Semantic organization

• Experiment 2
• Dani required to associate different colours with
  clan names did better with focal colours than
  with non-focal colours
• Conclusion
• same colours were focal for Dani as for US
  subjects
• therefore it is not language that makes certain
  colours easier to remember, but their perceptual
  salience

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Semantic organization

• Why do people form categories? (Rosch,1978)
• Cognitive economy want to obtain as much
  information from the environment as possible with
  the least effort
• the perceived world is a structured world our
  perceptions shape the concepts that we form

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Semantic organization

• Structure of categories
• categories have a horizontal and a vertical
  dimension
• horizontal--segmentation of categories at the
  same level of inclusiveness (e.g., sugar maple,
  silver maple)
• vertical--different levels of inclusiveness

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Semantic organization
11
Semantic organization

• Rosch argues that the basic level of organization
  is the most useful level for many purposes
  because it provides the most information for the
  least effort

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Semantic organization

• evidence to support hierarchical distinction
• common attributes experiment
• presented 9 taxonomies (e.g., tree, bird, fish,
  fruit, musical instruments, furniture, vehicle)
  at 3 levels
• participants were instructed to list all of the
  attributes they could think of that were true of
  the items listed
• few attributes at the superordinate level
  significantly more at the basic and subordinate
  levels

13
Semantic organization

• evidence to support hierarchical distinction
• motor movements
• subjects were presented same materials as in
  previous study, and were asked to describe motor
  movements
• basic objects were the most general classes to
  have motor sequences in common
• similarity of shape and identifiability of
  averaged shape were other lines of evidence to
  support hierarchical distinction

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Semantic organization

• How should concepts be represented?
• Classical theory
• what specifies a concept is some combination of
  semantic features (e.g., bird -- has feathers,
  wings, lays eggs, has a beak, etc.)
• this model has been formally developed by Collins
  Quillian, and Smith

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Semantic organization

• How should concepts be represented?
• Classical theory
• problem is that many naturalistic concepts
  (birds, fruits, games, tools, etc.) are not
  rigidly defined
• not all birds fly, not all games involve more
  than one person, are competitive etc.
• Wittgenstein argued that family resemblance may
  be a more useful way to think about category
  membership

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Semantic organization

• How should concepts be represented?
• The idea of family resemblance leads to the idea
  that category membership is not determined by
  rigidly defined categories but by resemblance to
  a typical member
• Rosch asked subjects to rate basic level words as
  being typical or atypical of a category (e.g.,
  robin, ostrich, chicken)

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Semantic organization

• How should concepts be represented?
• results subjects were very consistent in their
  responses (i.e, robin rated as typical)
• subsequent study showed that verification was
  faster as well (robin is a bird is faster than
  chicken is a bird) for typical than for atypical
  categories
• Rosch showed that typical instances had many
  features in common with other members of the
  category

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Semantic organization

• Semantic relatedness is a general finding in this
  literature
• prototypical members of a category are verified
  quickly
• related negative instances of a category are
  verified more slowly (e.g., potato is a tree
  takes longer to verify than does rifle is a tree)
  Kintsch, 1980
• comparison process seems to be critical not a
  simple category search

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Semantic organization
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Semantic organization

• Feature comparison models--Smith, Shoben, Ripps
  (1974)
• model assumes that concepts are represented by
  bundles of features, separated into those that
  are defining, and those that are characteristic
• e.g., bird -- defining -- feathers, lays eggs
• characteristic -- flies, two legs, migrates

21
Semantic organization

• Verify a sentence e.g., a robin is a bird
• model postulates that subject retrieves features
  associated with robin and with bird if there is
  a high degree of overlap respond yes
• if there is less overlap begin a second slower
  stage in which the defining features are
  compared if there is overlap respond yes if
  there is a mismatch respond no

22
Semantic organization

• Semantic network theories
• Collins Quillian
• hierarchical memory structure model (see page 203
  Radvansky)
• critical assumptions cognitive economy and a
  hierarchical model
• features that are true of all animals such as
  eating and breathing are stored at the highest
  level

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Semantic organization

• Semantic network theories
• prediction takes longer to respond to a true
  false question the further away the two types of
  information are stored

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Collins Quillian 1969
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Collins Quillian, 1969
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Collins Quillian, 1969

• Results were consistent with the hierarchical
  model with cognitive economy
• However, Conrad (1972) showed that if you control
  for relatedness, the level effect disappears
• also model has difficulty accounting for
  typicality effects of Rosch

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More recent semantic networks

• Spreading activation model of Collins and Loftus
• see your text

28
More recent semantic representations

• Schemas, frames, and scripts
• in 1932 Bartlett proposed that people remember
  new material in terms of existing structures of
  knowledge that he dubbed schemas or schemata
• schemas represent some aspect of the environment,
  or our experience, or beliefs
• learning was conceptualized as an active process
  in which people attempted to make sense of what
  they had experienced
• effort after meaning

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More recent semantic representations

• Schemas, frames, and scripts
• Bartlett studied effects of schemas on memory by
  investigating memory for a North American folk
  tale (structured but unfamiliar material)
• showed that the students tended omit material
  that was strange to them or to distort it in ways
  that fit their expectations
• criticism--model too vague to be testable

30
More recent semantic representations

• Schemas, frames, and scripts
• with the advent of computers and the cognitive
  approach to psychology scientists have begun to
  actively investigate these knowledge structures
• Minsky, Rumelhart, Schank, Abelson, Kintsch,
  Anderson

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More recent semantic representations

• Schemas, frames, and scripts
• characteristics of this approach
• this type of knowledge structure enables people
  to make sense of partially observed or described
  situations
• e.g., the man bought a candy bar. People
  typically would infer that in money was given in
  exchange for the candy bar
• e.g., the man drove in a nail

32
More recent semantic representations

• Schemas, frames, and scripts
• characteristics of this approach
• schemas have variables buying something in a
  store knowledge structure represents that it
  entails an exchange of money for a good however,
  the amount of money or the good is left
  unspecified
• hammering there is a tool (hammer), an object or
  recipient of the action (nail), an action
  (hammering motion), and an agent or person

33
More recent semantic representations

• Schemas, frames, and scripts
• characteristics of this approach
• schemas can embed within each other
• schemas operate at many levels of abstraction
• schemas represent knowledge or belief
• schemas are active recognition devices

34
More recent semantic representations

• Schemas, frames, and scripts
• Thorndyke (1977) studied the role of story
  structure on recall
• original version had a theme and then a narrative
  that elaborated the theme
• version 2 narrative then theme (after theme)
• version 3 narrative no theme
• version 4 randomly ordered

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Thorndyke 1977
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Thorndyke (1977)

• Conclusions
• level of recall depends upon
• degree of structure provided in the story
• level of importance of the information (hierarchy
  level)
• these two factors interact. Importance of
  information is evident only in structured stories

37
Schank scripts

• Schank and Abelson hypothesized that we have
  developed scripts that represent commonly
  experienced social events
• e.g., going to a restaurant
• e.g., going to a bank, taking a bus

38
Schank scripts

• Restaurant script
• Props restaurant, tables, menu, food, bill,
  money, tip
• Agents customer, waiter, cook, cashier, owner
• Entry conditions customer hungry, customer has
  money
• Results customer has less money, owner has more
  money, customer is not hungry

39
Schank scripts

• Restaurant script
• Scene 1 entering
• customer enters restaurant
• customer looks for table
• customer decides where to sit
• customer goes to table
• customer sits down
• Scene 2 ordering
• Scene 3 eating
• Scene 4 exiting

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Neuropsychology of semantic memory

• Visual agnosia (Lissauer, 1888)
• GL sustained a blow to the head
• complained of difficulty seeing
• examination showed normal visual acuity
• normal ability to copy objects
• recognition of objects was severely impaired but
  it was not a general deficit e.g., unable to
  recognize a whistle when presented visually, but
  able to recognize a whistle from its sound

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Neuropsychology of semantic memory

• Tactile agnosia (Beauvais, 1978)
• patient unable to recognize objects to touch, but
  could recognize objects when they were presented
  visually
• also patient was able to use objects
  appropriately
• these results suggest that semantic memory is not
  a single unitary system, but has a number of
  subcomponents associated with the modality of
  input

42
Neuropsychology of semantic memory

• Warrington Taylor (1978) showed that subjects
  with brain injury made two types of semantic
  errors in the visual modality
• access disorder--some subjects had difficulty
  recognizing a picture of an object (e.g., tennis
  racquet)
• degraded semantic store--other subjects
  recognized the object, but had difficulty
  recognizing which object was commonly associated
  with the object (e.g., a tennis ball)

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Neuropsychology of semantic memory

• Warrington Shallice (1979) proposed the
  following criteria to distinguish access versus
  degraded semantic store impairments
• consistency--if deficit is degraded semantic
  store, there should be consistency across test
  sessions (and type of test, Bayles)
• On the other hand if the problem is one of
  access, then one might expect that different
  types of retrieval cues might lead to retrieval
  of the item
• priming--patient should not show priming effects
  if there is a degraded store however, certain
  primes might facilitate access to items if the
  problem is one of access

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Neuropsychology of semantic memory

• Structure of semantic memory modality
  specificity or a single semantic store?
• one view holds that semantic memory consists of a
  single amodal system
• second view hypothesizes that there are separate
  systems for verbal, visual, and other types of
  information
• the evidence at this point is not yet entirely
  clear on this point

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Neuropsychology of semantic memory

• How are other types of information represented in
  semantic memory?
• Some evidence suggests that evaluative
  information is processed and stored in a
  different location than denotative information

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Case Description of AM

• Successful businessman prior to TBI
• Average to very superior general intellectual
  functioning
• Normal academic, attention, and executive
  function abilities
• Generally intact memory abilities
• Poor social judgment everything is positive

Park et al. (2001) Neuropsychologia
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(No Transcript)
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R. Temporal
Temporal
L. Amygdala
b
a
Amygdala
Frontal
c
d
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Attitude Priming Study of AM

• Purpose to investigate AMs evaluative rating of
  words
• Hypothesis impaired automatic evaluation of
  negative but not positive evaluative stimuli

Park et al. (2001) Neuropsychologia
50
Attitude Priming (continued)

• Method attitude priming paradigm
• Participants AM and 8 age - and education
  -matched controls
• Procedure
• Phase 1 rate single words as good or bad
• hypothesized positivity bias

Park et al. (2001) Neuropsychologia
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Rating of Words in Phase 1
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Response Latency to Phase 1 Words
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Phase 2
prime (pos or neg) 250 ms
blank screen 50 ms
target (pos or neg)
Task rate target as good or bad as quickly as
possible
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Control Priming Results Phase 2
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AM Priming Results Phase 2
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Summary of Attitude Priming

• Positivity bias in rating single words
• Slowed responses only to words rated as bad
• Priming in positive valence condition only
• Conclusion AM can automatically access positive
  but not negative evaluative information

Park et al. (2001) Neuropsychologia
57
Connotation Generation Study of AM

• Purpose to determine whether AM could access
  negative evaluative information when directed
• Task describe two positive and two negative
  features of single words (e.g., coffee)
• Same 92 words used as primes in Experiment 1

Park et al. (2001) Neuropsychologia
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Acceptable Good and Bad Connotations
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Semantic priming and AM

• Purpose of experiment
• to determine whether AM would show normal
  semantic priming
• prior research has shown that the latency to
  respond to a target is facilitated when the prime
  preceding the target is semantically related
  compared to when it is unrelated
• Method
• similar to Phase 2 of the first study

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Semantic priming and AM

• Method
• similar to Phase 2 of the first study
• task show prime-then target make a lexical
  decision about target item (word/nonword)

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Semantic priming and AM
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Conclusions

• Conclusions
• AM impaired in his automatic processing of
  negative evaluative information
• positivity bias
• no priming for negative evaluative words
• AM not impaired in his denotative or semantic
  processing of words
• suggests a dissociation between these two aspects
  of semantic memory