L15, 16 - Categories & Concepts

Question 1

What are categories?

Answer 1

• Categories are sets of things in the world that we represent as alike in some way, or treat as equivalent for some purpose.
• E.g: birds, things to take on a picnic, colours.

Question 2

What is a concept?

Answer 2

• Often used to refer to the representation of things about the category.

Question 3

What is categorisation and concept forming useful?

Answer 3

• Allows novel experiences to be understood as like previous experiences.
• Make predictions based on these classifications.
• Common reference (categories often have labels).
• Building blocks of more complex language.
• More efficient in cognitive economy.

Question 4

How are categories represented in Feature-Based Approaches?

Answer 4

• The majority of approaches assume categories are represented by unstructured collections of features, describing properties of individual objects.
• Doggo: four legged, furry, mammal, borks, friendly.

Question 5

What are the 5 main variants of the Feature-Based approach?

Answer 5

• Classical rule-based view.
• Prototype models.
• Exemplar models.
• Cluster models.
• Category boundaries.

Question 6

Outline the Classical Rule-Based view:

Answer 6

• Categories are represented by a set of defining necessary and sufficient features distinguishing members from non-members.
  E.g. Bachelor: unmarried man.
• People learn categories by holding candidate rules in mind and testing them to predict membership.

Question 7

Outline the Prototype Theory:

Answer 7

• There are often not necessary and sufficient conditions (criticism of Classical view).
  E.g. Pope, widower, man in long term relationship - all are not married but wouldn’t be labelled as bachelors.
• Prototypes are the collection of the average features across examples.
• Classification is about testing how similar new exemplars are to prototype.

Question 8

Outline the Exemplar Theory:

Answer 8

• Agrees with prototype theory in terms of classification about similarity rather than rules.
• Categories are represented as the collections of encoded exemplars.
• People generalise to things that are superficially quite like what they have seen before.
• Novel atypical stimuli are often classified as members if even a single encoded exemplar (Ostrich->weird af bird->helps to learn Emu).

Question 9

Outline the Cluster Model:

Answer 9

• Mix between Exemplar and Prototype Models (can store exemplars, can make abstractions).
• As exemplars are encoded, system predicts their category membership.
• Forms prototype-esque summary representations of similar examples.
• Atypical exemplars and similarities form sub-clusters.

Question 10

Outline the Category Boundaries Model:

Answer 10

• Instead of being concerned with summary representations, some theories focus on boundaries between categories.
• Leads to ideals/caricatures, also predicted by the error-driven learning of cluster models.

Question 11

What is the Structured Knowledge Approach?

Answer 11

• Concepts are not isolated from each other, but are parts of large knowledge structures that make them coherent and systematic.
• E.g: Bachelor - not merely an unmarried man, but a particular phase within a male hetero-normative life trajectory.

Question 12

What is the ‘Theory Theory’?

Answer 12

• To represent concepts we have theories and relations to prior knowledge for categorisation.
• e.g. man jumping in pool is seen as drunk.
• Prior knowledge can make categories coherent and easier to learn.

Question 13

What are the benefits of Theories over Feature based accounts?

Answer 13

• Feature accounts look at domain knowledge but focus on hierarchical taxonomies (dog->mammal->animal).
• Theories go further and provide casual connections and organise domains.

Question 14

What are Ad Hoc and Goal Derived Categories?

Answer 14

• Goals can make categories coherent, and even lead to constructing categories on the fly.
  E.g: “What do family pictures, jewellery, pets all have in common?” -> Things to grab in a fire.
• Different from feature-based categories is the importance of ideals.

Question 15

What are relational categories?

Answer 15

• Members represented by relational structures or roles within those structures rather than just features.
• E.g. husband (marriage), victim (robbery), solvent (catalysis).