Chapter 9-Conceptual Knowledge Pt. 1 Flashcards
Conceptual knowledge
Knowledge that enables us to recognize objects and events and to make inferences about their properties
Concept
Mental representation used for a variety of cognitive functions
Categorization
Process by which things are placed into groups called categories
-categories are all possible examples of a particular concept
Why categories are useful
Helps us understand individual cases not previously encountered
“Pointers to knowledge”
- provide general info about an item
- allow us to identify the special characteristics of a particular item
Definition approach to categorization
- determines 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
Family resemblance
- proposed to deal with the problem of definition
- things in a category resemble one another in a number of ways
Determining categories by similarity
-compare object to a standard
Prototype approach: the standard is determined by averaging category members
Exemplar approach: the standard is created by considering all of the examples you’ve seen before
Both approaches belong to family of resemblance
Prototype Approach
Prototype=typical
An average representation of the “typical” member of a category
Characteristic features that describe what members of that concept are like
An average of category members encountered in the past
Coglab: prototype
Each trial you are shown a dot pattern and asked to classify it as belonging to category A or category B
-each dot pattern was a variation of one of two fixed prototype random dot patterns
In test phase, a new set of dot patterns was presented
- the dot patterns in the testing phase were of four types
- one was the prototype that corresponds to the A category
- another was the prototype that corresponds to the B category
- the other two patterns were new variations of these prototypes
Coglab: prototype result
Reaction time for the unseen prototypes was faster than the reaction time for the unseen variations of the prototypes
Supports idea that people do develop some average of the random pairs
Posner and Keele experiment
They had three different prototypes
Participants see four distortions of each prototype, which are changed until they can discriminate them
Learn to categorize patterns with feedback
Posner and Keele results
Test on:
Old distortions=easy
New distortion=hard
New far distortion=hardest
Prototype=easy
Result: prototypes are explicitly extracted from examples, and serve as representation for category
High prototypicality
Category member closely resembles category prototype
Low prototypicality
Category member does not closely resemble category prototype
Rosch-The Prototype Approach
- Participants judged objects on a scale of 1 (good example of a category) to 7 (poor example)
- rated birds and furniture
Creates an index of high and low prototypicality
Gives us an independent variable that we can use in other experiments
Strong ______ resemblance between prototypicality and family resemblance
Positive
When items have a large amount of overlap with characteristics of other items in the category, the family resemblance of these items is high
Low overlap=low family resemblance
How to measure family resemblance
Rosch and Mervis
List the characteristics of the following items
-chair, sofa, mirror, telephone
Chair and sofa share a lot of common characteristics (mirror and telephone do not)
High family resemblance corresponds to high prototypicality (chair)
Low family resemblance corresponding to low prototypicality (telephone)
Typicality effect
Prototypical objects are processed preferentially
- high prototypical objects have faster RT
- sentence verification technique (apple/pomegranate)
Mervis et al
Prototypical objects are named first
E.g. Please list as many birds are you know
Rosch priming task
Prototypical category members are more affected by a priming stimulus
Hearing “green” primes a highly prototypical “green” which has the fastest RT
Table 9.1
Review in lecture notes
The exemplar approach
“Standard”=exemplar (which are examples of actual category members a person has encountered before)
- explain typicality effect
- easily takes into account atypical cases
- easily deals with variable categories
How is the exemplar approach similar to prototype view
Representing a category and do not define it
How is the exemplar approach different to prototype view
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)
Posner and Keele and the exemplar approach
- They had participants learn distortions from four prototypes with 1bit/dot distortion and 5bit/dot distortions
- tested using 7.7bits/dot distortion
- during test, those who got training with 5bits/dot distortion did better than 1 bit/dot distortion
If only doing prototype 1 and 5, they should have the same results if taking average which wasn’t true
Prototypes or exemplars
Early in learning people are bad at taking into account “exceptions” but later exemplars for the exceptions would be added to the category
Exemplars may work best for small categories
Prototypes may work best for larger categories
Hierarchical organization
Kind of organization in which larger, more general categories are divided into smaller, more specific categories to create a number of levels of categories
Global (superordinate) e.g. furniture
Basic e.g. table
Specific (subordinate) e.g. kitchen table
Basic level as “privileged”
- more common features given by participants for basic level category
- quicker to identify basic level category member as a category member
Listening properties of furniture, table, and kitchen table
From global to basic results in increase in info
From basic to specific results in little gain in info
More evidence that basic level is special
- people almost exclusively use basic level names in free naming tasks (think of demo)
- children learn basic level concepts sooner than other levels
- basic level is much more common in adult discourse than names for superordinate categories
- different cultures tend to use the same basic level categories
To fully understand how people categorize objects, one must consider
- properties of objects
- learning and experience of perceivers
Results of Tanaka and Taylor’s expert experiment
Experts used more specific categories to name birds whereas non experts used more basic categories
Semantic networks
- concepts are arranged in networks that represent the way concepts are organized in the mind
- Collins and Quillian
Node=category/concept
Concepts are linked
Model for how concepts and properties are associated in the mind
Cognitive economy
Shared properties are only stored at higher level nodes (in semantic networks)
Exceptions are stored at lower nodes
Inheritance: lower level items share properties of higher level items
