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Semantic Representation > Week 5 - Semantic Representation > Flashcards

Week 5 - Semantic Representation Flashcards

1
Q

What is semantic memory?

A

Database of what ‘things’ are.

Includes properties or features and its name. E.g. canary is yellow bird, Paris is the capital of France

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2
Q

What is conceptual (semantic) knowledge?

A

The idea of the object plus representation in mind

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3
Q

What are the two types of mental representation?

A

Analogical

Symbolic

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4
Q

What us an analogical presentation?

A

A mental representation that has a direct relationship to the object

It shares some of the physical characteristics of the object.

For example, picture of a violin or cartoon cat.

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5
Q

What is a symbolic presentation?

A

An abstract mental representation.

It does not correspond to the physical features of an object or idea.

For example, the word “violin” or “cat”.

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6
Q

What did Kosslyn et al (1978) study indicate about mental imagery?

A

Study used eye-tracking movements to observe participants looking at a map.

Demonstrated that participants spent more time than required to scan distances between two visual images that they knew to be longer

This was true even when the same amount of material falls between the initial focus point and the target.

Indicates that mental imagery can function as an internal spatial medium.

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7
Q

Which is a more useful representation type - symbolic or analogical and why?

A

Symbolic.

Are more suited to represent concepts than analogical representations, because of their flexibility

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8
Q

What is a concept?

A

The mental content of some object or event.

All the knowledge one has about that category, e.g. cats have whiskers, four legs, a tail.

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9
Q

What is a semantic classification?

A

Basic units of semantic memory,

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10
Q

What is a mental lexicon?

A

Single words and their meaning,

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11
Q

What are semantic association networks?

A

A set of concepts that are related to one another. Useful for remembering, guiding behaviour, reasoning and problem-solving.

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12
Q

What does categorization mean?

A

Grouping things based on shared properties; reduces the amount of knowledge we have to hold in memory, ex: musical instruments.

Thought of as the external content related to the concept.

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13
Q

What does Ross & Murphy’s (1999) sorting task tell us?

A

Context important for categorisation.

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14
Q

What does Barsalou (1983) say about categories?

A

Goals and purposes are important to define categories

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15
Q

What are the two dominant models on how categorisation occurs?

A

Classical and Prototype model of categorization

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16
Q

What is the Classical View (aka - Defining attribute model) of categorisation?

A

The idea that a concept is characterized by a list of features that are necessary and sufficient to determine if an object is a member of the category.

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17
Q

According to the classical view that are the two conditions for something to belong to a category?

A

o Necessary: each feature must be present

o Sufficient: If each feature is present that’s all you need to belong to that category

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18
Q

What is the significance for categorisation if the two conditions must be present?

A

o Membership within a category is an all-or-none basis
o All of category’s attributes equally important in defining that category
o All members of a category are equal in category membership

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19
Q

What is the main criticism for this classical view of categorisation?

A

Typicality effect: finding that people are quicker to make category judgments about typical members of a category than atypical members.

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20
Q

What did Rips et al, (1973) find about categories?

A

Participants had slower reaction times when making a category judgment for “penguin is a bird” compared to “robin is a bird”

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21
Q

What did Rosch & Mervis (1975) say about categories?

A

Some members are “more members” than others

22
Q

What is the Prototype Model of categorisation?

A

o Within each category, some members are more representative than others.
o Membership defined on the basis of a ‘typical’ or ‘likely’ set of features,

23
Q

What is the main difference between prototype model and classical view of categorisation?

A

Unlike classical view, doesn’t require the possession of all characteristics. Allows for more flexibility in concept formation

24
Q

What is the main criticism of prototype model?

A

Some concepts are not flexible and require more definition. Determined by definition rather than similarity (e.g., “triangle” or “even number”).

25
Q

What is the problem with the typically effect and in the prototype model?

A

Typicality is sensitive to context - two objects may have the same level of typicality but one may be more suited for certain contexts compared to the others). Category of ‘bird’ more likely to be given to chicken if seen in a farm than a city scene

26
Q

Which categorisation model better decribes categorisation process?

A

Not all categorization processes are the same. Some concepts may be better described by classic view, other by prototype.

27
Q

How are semantic representations in the brain stored and organised?

A

Distributed View: general agreement that knowledge of objects and concepts is widely distributed in the brain.

28
Q

How are semantic representations activated in the brain?

A

Concepts are a collection of properties (features), which activate different areas

29
Q

What evidence is there that supports distributed view?

A

Evidence from brain-damaged patients with category-specific deficits indicates that different object properties are stored in different brain areas.

30
Q

What does the distribution-only theory suggest?

A

No specific hub for semantic knowledge.

Concepts are described by perceptual and functional attributes that involve independent brain areas that are interconnected

Action, perception, language, motor areas can be activated during processes of concepts but there is no single ’core area’ responsible

31
Q

What does the distribution + plus hub theory suggest and why?

A

View that semantic memory is distributed BUT is underpinned by an ‘amodal’ hub for semantics, residing in the anterior temporal lobe (red area).

Modality-specific areas are interconnected but communicate ‘through’ a semantic hub.

32
Q

Why does Patterson et al (2007) argue that the semantic hub is necessary?

A

Modality specific processes cannot account for why we are able to make higher-order generalisations.

For example, scallops and prawns have similar conceptual overlap, yet we are able to make specific distinctions between them. Indicates higher-order function.

33
Q

What predictions does distribution-only theory make about semantic impairments?

A

No such generalized semantic impairment, since modality-specific aspects of the concept reside in different areas.

For example, semantic memory of the sounds of the concept would be impaired but not the picture of the concept

34
Q

What predictions does distribution-plus-hub theory make about semantic impairments?

A

Predicts that lesions to ‘the hub’ will lead to general, amodal, semantic impairments.

For example, objects, sounds, pictures, words associated with that concept would be impaired,

35
Q

What does acquired disorders of semantic memory tell us about conceptual knowledge?

A

All four conditions give useful clues about the nature and organization of conceptual knowledge, but from different angles

36
Q

What does semantic dementia tell us about conceptual knowledge?

A

Shows deficits across all semantic modalities and virtually all concepts (except numeric representations).

Leads to the disruption of semantic representations. E.g. Semantic deficits for producing and comprehending semantic vocabulary.

Evidence from picture categorisation tasks, colour and object recognition tasks and delayed copying tasks suggest cross-modal impairment.

Progression of disease correlated with degrees of impairment in task performance.

37
Q

What does Alzheimer’s disease tell us about conceptual knowledge?

A

Semantic memory is frequently affected in but typically at a later stage and to a more modest extent than episodic memory.

38
Q

What does Herpes simplex virus encephalitis (HSVE) tell us about conceptual knowledge?

A

Demonstrates category-specific semantic deficits.

HSVE causes lesions to the antero-medial temporal lobe.

Semantic deficit in HSVE is often category-specific, with relatively well preserved knowledge of man-made things but impaired knowledge of living things.

Patients have category-specific difficulties with living things rather than non-living things (e.g. naming and drawing).

Debate in literature if category specific deficits indicate sepea

39
Q

What does Stroke tell us about conceptual knowledge?

A

Stroke causes semantic Aphasia (SA) but not the same as semantic dementia (SD)

Both lead to anomia - poor performance on naming tasks.

SA suggests loss of access to semantic representations. No impairment to ATL

SD there is an actual loss of these representations. Impairment to ATL

40
Q

Where is the semantic hub thought to reside and how do we know?

A

In the anterior temporal lobe (ATL).

We know this because semantic dementia (SD) is characterized by focal lesions in the anterior temporal lobes (ATL).

Semantic dementia patients show a general semantic impairment, for every category of concepts across modalities.

HSVE patients have impairment in the antero-medial temporal lobe.

Stroke - anomia but no impairment to ATL.

SD - anomia plus ATL impairment.

41
Q

What is Anomia?

A

The failure to name objects, concepts and people, whether in response to stimulus
presentation or in spontaneous speech.

42
Q

What are the main differences between the performance on semantic tasks by stroke patients and patients with semantic dementia?

A

SD: benefit from ‘cueing’ e.g. they fail to name a lion from a picture, but if given the cue “L” they could probably name it correctly

Make associative (semantic) errors. 
Asked to name ‘milk’, they say ‘cow’

SA: Do not make associative errors or benefit from semantic facilitation, like cueing

43
Q

What does gradual loss tell us about semantic knowledge?

A

Gradual loss: Concepts deteriorate gradually, with some aspects of their meaning being lost before others

Evidence from Patient JL: Naming responses of living and non-living things deteriorated over time

Less able to give specific name over time

44
Q

What does partial loss tell us about semantic knowledge?

A

Loss of some aspects of meaning but not others, suggests concepts are represented as collections of properties or features of different category type.

Evidence from patients with semantic memory disorders

Indicates that concepts are not mental atoms. Otherwise they would be lost all at once.

45
Q

What are category-specific semantic deficits?

A

Brain damage affects certain categories of concepts and not others.

Problems most often with living things.

Problems with non-living things much rarer.

Evidence from patients with HSVE, for example, patient RC: category-specific difficulties with living things rather than non-living things (e.g. naming and drawing)

46
Q

What does neuropsychological evidence indicate about category-specific deficits and the semantic hub?

A

Category-specific regions in posterior areas

Category-specific deficits: evidence for independent neural systems to process modality-specific information.

The anterior temporal lobe (ATL) is the region where the amodal semantic memory is localized

47
Q

What does “temporal cortex lesion” studies tell us about category-specific regions?

A

Pobric et al. (2010) found that temporarily disrupting activity in the (ATL) and (IPL) causes specific impairments.

Anterior Temporal Lobe (ATL) - impairment to category-general naming (living things, tools)

Inferior Parietal Lobule (IPL) - impairments to naming man-made objects (tools – processing of praxis)

48
Q

What is ATL?

A

The anterior temporal lobe (ATL) is the region where the amodal semantic memory is localized

Pobric et al. (2010) found that temporarily disrupting activity in the ATL causes category-general impairments,

49
Q

What is ITL?

A

Pobric et al. (2010) found that temporarily disrupting activity in the ITL causes category-specific impairments.

Other modality-specific areas underpin specific modalities (e.g. motion).

Modality-specific regions like IPL provide the basic “ingredients” (sensory, motor, verbal etc.), while the ATL supports an additional amodal representation.

Recent evidence suggests the ATL is graded.

50
Q

What is ATL Important for?

A

Anterior temporal lobe is important for semantic representations, i.e., the content of semantic knowledge.

51
Q

What are Prefrontal and Temporo-parietal areas important for

A

Prefrontal and Temporo-parietal areas are important to access and manipulate semantic representations

Semantic Representation (1 decks)

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