Lecture 9 (Ch.9 knowledge) Flashcards
What is knowledge?
o Memory for facts, understanding, other information…
o AKA: long-term, explicit, declarative, semantic memory
o Associated with concepts
o Mental representation of a class or individual
What is conceptual Knowledge?
Ability to recognize objects and events
Make inferences about properties
Categories
Pointers in knowledge Shorthand version of more general information about items Also helps to characterize differences - Cases not previously encountered - Distinguish special characteristics
Definitional Approach
Using formal definition to determine membership
- Problems: doesn’t work for some categories
Family resemblanc
similarities b/w members (we can do the same to categorize things)
Prototype Approach
Prototype: Average or typical representation of something.
Characteristic features .
Average of members encountered
Idea of the “perfect” or ideal member (use for comparison)
High vs. Low prototypicality
High: resembles prototype a lot
Low: doesn’t really resemble prototype
Typicality effect
Higher prototypicality = faster naming
Exemplar approach
Similar to prototype
- Represents category without defining it BUT
- Use of multiple examples (rather single prototype)
- Actual category members (not abstract averages)
- Comparison of new items with exemplars
- Explains typicality effect
- Takes into account atypical cases
- Easily deals with variable categories (ex: games)
Do we use prototype or exemplars more?
Some evidence – likely use both
May depend on
- Category size?
•Prototypes better for larger categories
•Exemplars – smaller, more specific categories
- Initial vs. later learning?
•At first – prototypes –> exemplars (ex: is a dolphin a fish?)
Hierarchical
Cetegories are hierarchical From superordinate (Global), basic, subordinate (specific)
Semantic networks
Associations within categories.
Lower level items share features with higher level items
General Model (Collins and Quillian)
The network consists of nodes that are connected by links. Each node represents a category or concept, and concepts are placed in the network so that related concepts are connected. In addition, a number of properties are indicated for each concept.
It is hierarchical
Cons: Doesn’t explain typicality effect
Connectionists model
Approach to creating computer models for representing cognitive processes.
parallel distributed processing (PDP) models propose that concepts are represented by activity that is distributed across a network.
Can account for network changes (learning)
Adjusting weights at connections (synapses) –>Affects strength of next signal
Steps in connectionist model
Step 1 – environment --> input Step 2 – input --> hidden •Various routes •Changeable connection strengths Step 3 – Hidden --> output
How do we learn
o If provided with correct response
- Can correct errors
- “Error signals”
- “Back-Propagation”
- Adjust Strengths of Connections
Properties of Connectionist Model
Learning: initially slow but generalized
Can use many different types of inputs
Concept is distributed across network
Overtime: can use various routes to arrive to the same output
Robust and resistant to change (graceful degradation)
Embodied Approach
our knowledge of concepts is based on reactivation of
sensory and motor processes that occur when we interact with the object
Mirror Neurons*
sensory-functional (S-F) hypothesis
the sensory-functional (S-F) hypothesis:t our ability to differentiate living things and artifacts depends on a
semantic memory system that distinguishes sensory attributes and a system that distinguishes function.
semantic category approach
proposes that there are specific neural circuits in the brain for some specific categories
Multiple factor approach
multiple-factor approach but this approach focuses not on brain areas or networks that are specialized for specific concepts but on searching for more factors that determine how concepts are divided up within a category.
Semantic Dimensia
Progressive loss of semantic and conceptual knowledge - Both verbal/nonverbal
Bilateral Anterior Temporal Lobe degeneration
Typically start with naming problems
But in the presence of relatively spared episodic memory
Progressively – more general problems w/verbal and nonverbal concepts
Abstract vs. concrete
What the approaches agree on
all of the approaches agree on is that information about
concepts is distributed across many structures in the brain
