What are the two different kinds of knowledge?
-Declarative knowledge - knowing that...
-Procedural knowledge - knowing how..
How do we organize declarative knowledge?
Concepts, categories and schemas
What is a concept?
One of the ways we organize declarative (or knowing that...) knowledge. It is the fundamental unit of symbolic knowledge - knowledge of correspondence between symbols (3) and their meaning (three). Concepts relate to other concepts.
A mental representation of an item and associated knowledge and beliefs.
When do we use concepts?
1. to combine them to form complex thoughts
2. for communication
3. to make inferences
4. to create categories
What are the different types of categories?
natural, artifact, and ad hoc.
natural categories occur naturally (plants, trees)
artifact categories are created by humans (hammer, computer)
ad hoc categories are created individually to suit a need (things you need to be happy)
What is a natural category?
One of the different ways in which we organize categories which organize declarative knowledge. Has to do with things that occur naturally.
What category is created by the individual to suit their own specific needs of organizing declarative knowledge?
Ad hoc category
-superordinate: broadest way to categorize a category (animal)
-basic level: largest number of features that set it apart from other concepts at same level, used most often in discourse (bird)
-subordinate: specific way to categorize - robin
Evidence for Basic Level
-almost always use basic-level names in free-naming tasks
-children learn basic-level concepts sooner than other levels
-basic level is more common in adult discourse than names for superordinate categories
How do people organize objects into categories?
1. Defining features
4. Theory-based categorization
5. Hierarchically semantic networks
Describe the theory of defining features:
a theory on how people decide what to put in a category. Must have a "defining feature" in order to be considered a member of a certain category.
-What are the defining features of a college student?
**this theory makes categories orderly and systematic
Which theory of organization of objects into categories describes defining features?
Describe two limitations of defining features theory:
It is difficult to specify necessary features of some concepts. Example - what is the defining feature of monster? What is the defining feature of a college student?
Also typicality effects - some things are better examples of a concept than others...a robin is a more typical bird than an ostrich
What are typicality effects? To which theory does it relate to?
Defining features theory. Typicality effects are a problem within the theory because some things are better examples or more typical examples of concepts than others. Robin is more typical bird than an ostrich.
create a prototype - abstracted representation of a category containing salient/common features that are true of most instances.
-characteristic features: describe the prototype, but are not necessary for it
Characteristic features vs. defining features
characteristic features - prototype theory component that bases categories on common features that are true of most instances
defining features - DF theory, consists of one defining feature - very limiting
Positives of Prototype theory
-deals well with fuzzy concepts - or categories that can't be easily defined. to categorize, compare it to the prototype you already have.
-multiple examples convey the idea of what the concept represents
-bird concept exemplars: robin, duck, hawk
-the more similar a specific exemplar is to a known category member, the faster the exemplar will be categorized
Exemplar vs. Prototype
-Both have a representation and not a definition
-But for exemplar the representation is specific not abstract like in prototype
-To categorize, compare to stored specific examples not general prototype
Combine Feature-Based and Prototype theories:
-each has a prototype or a core
-Prototype: characteristics typical of examples
-Core: defining features that item must have
Example: a thief
-Core: steals something
-Prototype: features we tend to associate with thieves (mask, dark clothes etc.)
Theory based categorization
Use experience to construct an explanation for a phenomena. Works well for complex concepts. Suggests that people understand and categorize concepts in terms of theories or general ideas (possibly implicit) that they have about that concept
idea that certain categories have an underlying reality that cannot be observed directly
Semantic Network Model
Nodes represent concepts in memory and relations represented links among sets of nodes.
Collins & Quillian's Model (1969)
-Structure is hierachical
-Time to retrieve information is based on the number of links
-Cognitive economy: properties stored only at highest possible level
-Inheritance: lower-level items also share properties of higher-level items
What is cognitive economy?
Component of semantic network model theory that properties are stored only at highest possible level.
What is inheritance?
Component of semantic network model theory that lower-level items also share properties of higher-level items.
Example of Collins & Quillian's model
-semantic network model theory
1st level = animal: has skin, can move around, eats
2nd level = bird:has wings or fish: has gills
3rd level = canary: can sing, ostrich: can lay eggs etc.
Neuroscience evidence for Semantic Networks
-Alzheimer's patients: in word stem completion tasks patients with more progressed Alzheimer's are less likely to complete the stem with the prime word
-Patient H.M. (medial temporal lobe resection) = inability to form new episodic memories, impaired ability to learn new semantic memory...but could learn SOME new semantic information
Cultural differences in categorization
Task: sort terms representing concepts. Those with higher IQ sort concepts hierarchically and those with lower IQ sort concepts functionally
organize our knowledge, help us with encoding, storage and recall and allow us to make inferences.
Framework used to organize concepts. Models of the external world based on past experience. For concepts underlying situations, events or sequences of actions (scripts for dining at a restaurant). If-then relationships. Abstraction that allows particular objects or events to be assigned to general categories
What are schemas?
Abstraction that allows particular objects or events to be assigned to general categories. Models based on past experience, underlying situations/events and reasoning skills
subtype of schemas. Type of schema about events that captures general information about routine events and have typical roles. Going to a restaurant, customer, server, cook etc.
Tuckey and Brewer 2003
studied the impact of schemas on eyewitness memory. One factor manipulated was the ambiguity or schema consistency of film crime watched. Film activated bank robbery schema. Results showed lower recall and more schema-consistent intrusions/assumptions occuring in the ambigious condition
Bower, Black & Turner (1979)
Participants read stories about different schemas (going to doctor, dentist) Healthcare schema activated for both. Asked about events that happened (actually happened, consistent with schema but not in story, unrelated events). Participants were confident about actual events they read and schema consistent events not actually in story.
-ideas contained in the schema become a part of the memory with items and events actually experienced
Brewer & Treyens (1981)
Memory for graduate student's office, participants recalled expected objects or highly unexpected objects. goes with schema or goes against schema.