LPI T7 Flashcards
What’s the key takeaway about categorisation
may not be a single process, and different kinds of categorization may lend themselves to different theoretical treatments.
SEMANTIC KNOWLEDGE
Knowledge about objects and their properties, and of relationships between and among them, including knowledge of word meanings. General encyclopaedic knowledge is sometimes also included.
TAXONOMIC HIERARCHY
A structured set of concepts linked together with class-inclusion relationships.
How does taxonomic hierarchies relate to semantic dementia and semantic development
Children and dementia patients work in opposite directions one expanding on the superordinate concepts and the other losing the specific concepts
Category
A set of objects in the world that can be grouped together
Categorisation:
Process of placing concepts into groups called categories, based on their characteristic features
Concept
A mental representation of a category, used for a variety of cognitive functions including memory, reasoning, and using language. A classical view is that concepts provide definitions of their corresponding category.
What is similarity?
The degree to which features/elements of an object or stimulus ‘match’ one another (Braisby & Gellatly, 2012).
What is typicality?
The degree to which an object or stimulus is the best or most representative example of a category or concept
INTERNAL REPRESENTATION
In a PDP network , a pattern of activity that arises across a layerof hidden units. When a network is presented with a given input, the pattern of activity arising across its hidden layer is the internal representation of that input.
*See The Connectionist approach slides in Topic 7
HIDDEN UNITS
Hidden and theoretical gateways between input and output that represent differentiated partterns of activation
Parallel Distributing Processing (PDP) framework
the brain does not function in a series of activities but rather performs a range of activities at the same time, parallel to each other.
propagation of activation
Semantic information is not stored as such but instead is reconstructed in response to probes in a process called pattern completion.
What are the three major points of criticism for the classical view?
- concepts are definitions of categories are undermined by arguments that many categories cannot be defined and cannot readily explain typicality effects, borderline cases, and intransitivity
- People may categorise things in different ways according to their goals and the nature of their knowledge so as to fit the claims of different theories
- Different types of categories have different properties and so may require different theoretical treatments
What is categorisation in the prototype view determined by?
similarity to the prototype, which also explains the typicality
What are the concerns concerning the prototype view?
- cannot explain the context-sensitivity of typicality
- does not explain how prototypes might combine in complex concepts
- the unsettled nature of whether the existence of typicality effects implies a prototype organization
What is the theory-based view about?
can explain the non-independence of attributes in concepts and dissociations between categorization and similarity while offering an account for similarity
What criticism of the theory-based view?
it is not clear how theories might combine complex concepts, and the notion of a theory is unspecified
How does categorisation work in the classical view?
- things belong to categories because they possess certain properties in common.
- Possession of the common aspect is important for category membership
- Possession of the common properties is sufficient for category membership
- e.g. Bachelors (unmarried, adult, male) has multiple categories
What is a GOE?
Goodness of exemplar
Typicality rating method
What is exemplar theory?
concepts are instead representations of the individual members ( or exemplars) of the category that we have experienced
What is the issue surrounding a lack of definitions (Wittgenstein, 1953)?
- Categories seem to group common aspects together, but as a whole, on a specific level, you’ll find no truly common properties like in games
- Categories are indefinable
What does transivity mean?
Members of category A also belong to B, B → C = A → C
How does the classical view relate to typicality (representativeness)?
All members must meet the definition criteria and be equal in their quality as members but there are systematic differences
When does an item belong to a category?
As long as there is not a significant divergence between it and the prototype =similarity
What is the prototype theory?
Born out of the limitations of the classical view and centres the best category member who acts as a representative
What do McClelland and Rogers mean by the propagation of activation? (p.312)
Semantic information is not stored as such but is reconstructed in response to probes in a process called pattern completion. These patterns are activated if one tries to retrieve said knowledge, whereby the strength of these connections depends on experience. → Think Hebbian Synapses
What are the key findings of AAB and ABC renewal research?
You do not need to return to an original context for a conditioned behaviour to occur
What do typicality effects do?
Expose the insufficient differentiation between members but not contradict the classical view as a whole because it is all-or-nothing. There are no borderline cases that cannot be clearly distinguished (McCloskey & Glucksberg,1978)
What approach did Quillian propose? (p.310)?
- Concepts organised in a hierarchical order ranging from a general and encompassing superordinate to increasingly specific concepts
→ Propositions applicable to all members of a superordinate category could be stored only once, at the level of the superordinate category
How does this aspect challenge the classical view?
It’s transitive, but peoples’ judgments aren’t consistent (Hampton, 1982 Is a car seat furniture?)
What is the difference between prototype and classical theory?
Prototype theory allows a degree of mismatch of the qualities while classical theory doesn’t → level of matching = typicality
What do Brooks et al. (1991) (skin disorder categorisation) and Allen and Brooks (1991) show (cartoon animal picture organisation)?
Exemplar so previous information is hard to ignore
What’s typicality?
the degree to which an object or stimulus is the best or most representative example of a category or concept
How is the parallel distributed processing (PDP) model trained? (p.313)
connections are initially set to small random values so that activations produced by a particular input are weak and undifferentiated. The network is trained by presenting it with experiences based on the information contained in Quillian’s hierarchy
What is a hidden unit? (pp.313–14)
The hidden units are not anything physically ‘real’. The are abstract concepts that allow us to capture complex relationships. ➜ They act like gateways between input and output
According to McClelland and Rogers, why do infants first develop basic-level (intermediate-level) descriptions? (p.317)
- Parents use superordinate words more frequently than specific ones
- The clustering of objects in the world into tight-knit intermediate-level groups within superordinate categories
- the tendency for parents to use intermediate-level words more frequently than more general or more specific words when speaking to children; few items — such as dogs — are discussed far more frequently in such speech than are related items — such as other land animals, birds or fish
- All this leads to more weighted connections and more robust networks
What is the overestimate of high-density contingencies?
In control tasks, sometimes referred to as operant tasks (Dickinson et al., 1984), but also predictive tasks in which participants judge relationships between symptoms and diagnoses, participants have strong a priori expectations that events are associated
What is coherent covariation? (p.318)
Consistent co-occurrence of a set of properties across different objects. The concept is distinct from simple correlation in that it generally refers to the co-occurrence of more than two properties. For example, having wings, having feathers, having hollow bones and being able to fly all consistently co-occur in birds.
