Chapter 9: Conceptual knowledge Flashcards
Conceptual knowledge
knowledge that enables us to recognize objects and events, and to make inferences about their properties
Concepts
the mental representation of a class or an individual; categories of events, objects, and abstract ideas
Category
a set of all possible examples of a particular concept
Definitional approach to categorization
we decide if an object is a member of a category if it meets the category’s definition
Limitations of the definitional approach
(1) not all members of categories share the same defining features, (2) it is computationally intense to match objects on many feature dimensions
Family resemblance
members of a category resemble one another in a number of ways; allows for some variation within a category
Prototype approach to categorization
membership in a category is determined by comparing the object to a prototype that represents the category
How is a prototype formed?
averaging together the common instances of a category to get the typical member
Typicality
a member’s extent of resemblance from the category’s prototype
When is family resemblance of objects high?
when there is a large overlap between their characteristics or when they are more prototypical
Sentence verification technique
participants identify if statements are true or false to determine how rapidly they can categorize objects
Typicality effect
the ability to judge highly prototypical objects more rapidly
Priming
when presentation of one stimulus facilitates the response to another stimulus that usually follows closely in time
Why is priming more helpful when stimuli is more prototypical of the prime category?
priming leads participants to create images of prototypes that facilitate their response to the highly prototypical stimulus
Exemplar approach to categorization
determining whether an object is similar to examples or actual members of a category called exemplars
2 advantages of exemplar approach
can more easily (1) account for categories with loose or atypical members and (2) deal with categories that are hard to average
Hierarchical organization
large, general categories are divided into smaller, more specific categories in which any object can fit into several categories
3 levels of categories (Rosch)
superordinate or global level, basic level, and subordinate or specific level
Why is the basic level of categories psychologically special?
going above it (global level) results in a large loss of information and going below it (specific level) results in little gain of information
Semantic network approach
concepts are arranged in hierarchical networks that consist of nodes, which each represent a category or concept, that are connected by links and have distinct properties; a process model so it doesn’t mirror physiology
Cognitive economy
shared properties are only stored at higher-level nodes to avoid redundancy and exceptions are stored at lower nodes
Spreading activation
activation of one node spreads to other connected nodes, priming and facilitating their retrieval
Limitations of Collins & Quillian’s semantic network approach
(1) doesn’t explain typicality effect, rather proposes that both typical and atypical members result in equal reaction times; (2) uncommon nodes are skipped and don’t benefit from spreading activation
Connectionist approach
computer models (i.e. parallel distributed processing models) are created to represent cognitive processes and mimic the way brains work
What are units in a connectionist network?
they represent concepts and their properties and, like neurons, are connected by patterns of activity that are each assigned a weight
Connection weight
degree to which the next unit is activated or inhibited
Input units
units activated by stimuli from the environment or stimuli presented by the experimenter; send signals to hidden units, which send signals to output units
What 2 things do activation of units in a network depend on?
(1) the signal that originates in the input units and (2) the connection weights throughout the network
Back propagation
erroneous responses in property units cause an error signal to be send back through the network to provide information about how connection weights should be adjusted
Graceful degradation
disruption of performance in connectionist networks due to brain damage occurs only gradually because concepts are distributed across many units
How does connectionism explain the generalization of learning?
training a system to recognize properties of one concept also provides information about related concepts due to similar patterns of activation
Category-specific memory impairment
loss of ability to identify one type of object but but retained the ability to identify other types of objects (e.g. animals and non-animals)
Sensory-functional hypothesis
our ability to differentiate living things and artifacts depends on a memory system that distinguishes sensory attributes and another that distinguishes functions
Multiple-factor approach
factors beyond sensory and functional distinguish concepts within a category
What objects are associated with both performed actions and sensory properties?
musical instruments and some mechanical devices
Crowding
difficulty recognizing living things is due to difficulty distinguishing between the similar features that animals share, not due to category-specific impairment
Semantic category approach
semantic categories are mapped to distinct brain networks or neural circuits and are distributed over a number of cortical areas
Embodied approach
our knowledge of concepts is based on reactivation of areas responsible for the sensory and motor processes that occur when we interact with an object
Semantic somatotopy
the correspondence between the location of brain activity activated by reading words related to specific parts of the body and actual movements
Criticisms for embodied approach
(1) contrary to what it predicts, ability to represent motor activity associated with actions is not necessary for recognizing objects; (2) not well suited to explaining knowledge of abstract concepts
Semantic dementia
general loss of knowledge for all concepts with an equal deficit for both living things and artifacts due to damage in the anterior temporal lobe
Hub and spoke of semantic knowledge
areas of the brain that are associated with specific functions (spokes) are connected to the ATL, which serves as a hub that integrates information from these areas
What deficits are caused by damage to spokes vs the hub?
damage to specialized brain areas/spokes cause domain-specific conceptual deficits while damage to the ATL causes general deficits (semantic dementia) as seen in TMS studies
