Conceptual Knowledge II: Concepts Organized in the Mind Flashcards
Concepts Definition?
“categories of objects, events, and abstract ideas”
Broader than a category
Are concepts really organized in hierarchies? The semantic network approach says…
The semantic network approach says yes!
- Concepts are arranged in networks
- Networks are hierarchical
Semantic Network Approach - Collins & Quillian(1969) hierarchical model? *Cognitive economy
- Categories/concepts are called nodes
- Properties of each concept are indicated at nodes
- Move up in the network to find more properties
Cognitive economy:
Shared properties are only stored at higher levels to avoid redundancy - Exceptions stored at lower nodes
Semantic Network Approach - Collins & Quillian(1969) experiment?
- Participants respond to true or false statements
- “A canary is a bird”
- Each statement contains two nodes
- IV: distance between nodes
Results suggest people respond faster when nodes are closer together
Supports Collins & Quillian’s hierarchical model
Collins & Quillian’smodel intended to explain how concepts are functionally linked, not physiologically linked… Spreading activation?
Spreading Activation:
Activation of one node spreads to other connected nodes
(Priming by Spreading Activation Example) Seeing a list of multiple words relating to one topic but….
Not the word itself, however one think they do
Snooze
Pillow
Moon
-> Think we saw sleep
Limitations of Collins & Quillian’s model of semantic network approach?
- Doesn’t explain typicality effect
- Uncommon nodes are “skipped”, do not benefit from spreading activation
Connectionist Approach?
- Connectionist models are implemented on computers, intended to mimic the way brains work and learn
- Modern machine-learning algorithms use this (esp. “neural network” algorithms)
- Concepts are represented by a distributed network of activation
Connectionist Approach… Instead of “nodes,” there are “units” (like neurons)?
- Units are connected (like axons)
- Connection strength is assigned a weight
Weight: degree to which next unit is activated or inhibited
Concepts are learned by experience in identifying them
- Errors cause readjustment of connection weights
Support for the Connectionist Approach?
- Connectionist models really work!
- Computers can learn to identify things (computer vision loves this)
- Concepts are represented in a functional way
Support for the Connectionist Approach - Evidence from brain damage?
- Damage usually only causes partial loss of concepts
- Supports idea that concepts are distributed widely
Support for the Connectionist Approach - Evidence from learning?
- Generalisation occurs when e learn concepts that are similar to previously known ones
- Connectionism has generalisation built in
How Concepts are Represented in the Brain - Sensory-functional hypothesis?
Sensory-functional hypothesis:
Living and nonliving things are represented by different systems
Evidence by some patients having category-specific memory impairment
- People could identify tolls, but not animals
But there are many exceptions; distinction between sensory and functional representation is too simple
How Concepts are Represented in the Brain - Multiple-Factor approach?
Multiple-Factor approach:
Like sensory-functional hypothesis, but more factors use to distinguish concepts
E.g.: colour, smell, type of motion, how to use
How Concepts are Represented in the Brain - Semantic-Category approach?
Semantic-Category Approach:
Semantic categories are mapped to distinct brain networks
Distributed, but some are visible with FMRI scans
How Concepts are Represented in the Brain - Embodied approach?
Embodied Approach:
Concepts (esp. sensory and action concepts) are represented by the same networks responsible for sensing them and motor interaction with them
FMRI studies validates this
How Concepts are Represented in the Brain - Hub-and-Spoke Model?
- Anterior temporal lobe (ATL) is the “hub” integrating information
- ATL is the nexus of other types of representations distributed throughout the brain
- Concepts are represented by linking the specific networks (e.g., visual, motor, auditory) together by a central point in the ATL
Support for the Hub-and-Spoke Model?
- Damage to specialized brain areas can cause domain-specific conceptual deficits
- Damage to the ATL can cause general conceptual deficits, called semantic dementia
- Evidence from Transcranial Magnetic Studies
