Flashcards in Chapter Nine - Knowledge Deck (113):
knowledge that enables us to recognize objects + events
-make inferences about their properties
-mental representation used for a variety of cognitive functions
process by which things are placed into groups
What are categories?
all possible examples of a particular concept
Concepts provide ______ for categories
Why are categories useful?
-helpful to understand individual cases not previously encountered
-"Pointers to knowledge"
How are categories pointers to knowledge?
-categories provide a wealth of general information about an item
-allow us to identify the special characteristics of a particular item
How do we determine category membership?
-whether object meets definition of the category
What is family resemblance?
-proposed idea to address problem that definitions often do not include all members of a category
How does family resemblance relate to categorization?
-things in a category resemble one another in another of ways
-allows for some variation within a category
Categorization may be based on _____
determining how similar an object is to some standard representation of a category
What is a prototype
-average representation of the typical member of cate
Prototype approach to categorization
-membership in a category is determined by comparing the object to a prototype that represents the category
What is an example of the prototype approach?
-not all birds are like robins, blue jays, or sparrows
-owls and penguins are also birds
Who is Rosch?
What was his experiment?
-S saw a category title (ex birds) + list of ~50 members of the category
-S asked to rate extent to which each member represented category title
What is high-prototypicality?
-category member closely resembles category prototype
EX: "bird" = robin
What is low-prototypicality?
-category member does not closely resemble category prototype
EX: "bird" = penguin
What did Rosch and Mervis's experiment test?
-test how well do good + poor examples of category compare to to other items within the category
How did Rosch and Mervis's experiment work?
-for each common object, list as many characteristics/attributes
What does it mean when items have a large amount of overlap with characteristics of other items in the category?
-family resemblance of these items is high
EX: good examples of furniture = chair, sofa
poor examples = mirror
There is a strong positive relationship between _____ and _______
-prototypicality, family resemblance
What does low overlap between items mean?
-low family resemblance
What is the typicality effect?
-prototypical objects are processed preferentially
How are highly prototypical objects judge?
EX: sentence verification technique
an apple is a fruit (y/n)
a pomegranate is a fruit (y/n)
What type of objects are named first?
What happens when asked to list as many objects in a category as possible?
-tend to list most prototypical members first
What are prototypical category members more affected by?
-a priming stimulus
How does a priming stimulus work?
-S heard the prime (ex: green)
-two seconds later: saw pair of colors side by side
-asked to press a key as quickly as possible if two were the same
-hearing "green" primes a highly prototypical green
What is the exemplar approach? (2)
1. concept represented by multiple examples
(rather than a single averaged prototype)
2. examples are actual category members
How do you categorize according to the exemplar approach?
-compare new item to stored examples
-this approach can explain Rosch results
How is the exemplar approach similar/disimilar to the prototype view?
similar: representing a category is not defining it
different: representation is not abstract (descriptions of specific examples)
What effect does the exemplar approach explain?
How does the exemplar approach take into account atypical cases?
-rather than comparing a penguin to an "average" bird
-remember that there are birds that don't fly
Exemplars may work best for _____ categories
Prototypes may work best for _____ categories
What does Rosch's research indicate about categories?
-different levels of categories
-from general ("furniture") to specific ("kitchen table")
What are the three levels of categories?
1. superordinate level (global level): "furniture"
2. basic level: "table"
3. subordinate level (or specific level): "kitchen table)
What is hierarchical organization?
-organization in which large/more general categories are divided into smaller, more specific categories
What was Rosch's experiment about levels of categorization?
-S were asked to list as many features as they could that would be common to all/most objects in category
What is the result of going above basic level results?
large loss of information
What is the result of going below basic level?
little gain of information
The basic level is ____ special
How is the guitar/fish example evidence that the basic-level is special?
-when S asked to name a guitar and a fish
-named them by their basic level name
-guitar rather than electric guitar (specific) or musical instrument (global)
-fish rather than trout/animal
How does culture paly into the results of Rosch's experiment?
-there is a category level (called basic"
-reflects college undergraduates' everyday experience
What was Coley, Medin + Atran's experiment?
-asked both undergraduates + horticulturists to walk around campus
-name as specifically as possible 44 different plants
What was the result of the Coley, Medin + Atran experiment?
-75% of undergrads used trees
-horticulturalists used "specific" categories like "oak"
What was Tanaka and Taylor's experiment?
-asked bird experts + non-experts to name pictures of objects
What were the results of the Tanaka/Taylor experiment?
-experts responded by specifying the birds' species
-experts learned to pay attention to features of birds than non-experts were unaware of
What are 2 important factors in categorization?
1. people's knowledge
2. properties of objects
What are semantic networks?
-concepts are arranged in networks that represent the way concepts are organized in the mind
What did Collins and Quillian develop?
-model for how concepts + properties are associated in the mind
-hierarchical model (more specific to more general)
What is a node?
What is inheritance?
-lower-level items share properties of higher-level items
What is the cognitive economy?
-shared properties are only stored at higher-level nodes
_____ are stored at lower level nodes
according to the hierarchical organization, which concepts are at the top and which are the bottom?
-general concepts at the top
-specific ones at the bottom
What is a testable prediction?
-time it takes for a person to retrieve information about a concept should be determined by the distance that it must be traveled through the network
EX: takes longer to answer "yes" to a canary is an animal, compared to canary is a bird
What is activation?
arousal level of a node
What happens when a node is activated?
-activity spreads out along all connected links
What happens to concepts that receive activation?
-primed and more easily accessed from memory
What is the Lexical decision task/
-participants read stimuli
-asked to say as quickly as possible whether the item is a word or not
What were the results of Meyer and Schvaneveldt's lexical decision task?
-reaction time was faster for pairs that were closely associated
What is a criticism of Collins and Quillian?
1. cannot explain typicality effects
EX: model predicts equal fast RT for both canary and ostrich as they are one node away from bird
2. evidence that people store specific properties of concepts right at the node for the concept
3. some sentence-verification results are problematic for the model
What is the typicality effect?
reaction times for statements about an object are faster for more typical members of a category
What are new approaches to the semantic network due to?
1. criticism of semantic networks
2. advances in understanding how information is represented in the brain
What is connectionism?
-approach to creating computer models for representing cognitive processes
What is connectionism also called?
-parallel distributed processing
-knowledge represented in the distributed activity of many units
______ determine at each connection how strongly an incoming signal will ________
weights, activate the next unit
what are lines?
connections that transfer information between units (axons)
what are output units?
-receive input from hidden units
what are units
-inspired by neurons in the brain
-patterns of activity in units represent concepts + their properties
what are input units?
units activated by stimuli from the environment
what is connection weight?
-how signals sent from one unit either increase/decrease the activity in the next unit
What are high connection weights?
-result in strong tendency to excite the next unit
What are the 5 aspects of the connectionist approach?
2. connection weight
4. output units
5. input units
What are negative connection weights?
-can decrease excitation
-or inhibit activation of the receiving unit
What are the 2 things the activation of units depends on?
1. signal that originates in the input units
2. the connection weights throughout the network
How is a stimulus represented according to the connectionist approach?
-by the pattern of activity that is distributed across the other units
What is the learning process for the connection approach?
-connection weights have to be adjusted in order for the network to operate properly
How does learning occur in the connectionist approach? (3)
1. network responds to stimulus
2. provide with correct response
3. modifies responding to match correct response
What is error signal?
-difference between actual activity of each output unit + correct activity
What is back propagation?
-error signal transmitted back through the circuit
What is the purpose of error signal?
-indicates how weights should be changed to allow the output signal to match the correct signal
The process ____ until the error signal is _____
What is the initial state of the units in the connectionist approach?
-initially weak and undifferentiated activation of property units
-with many errors
What is the process of error signal in the connectionist approach? (3)
1. error signals are sent back
2. changes are made in connection weights
3. each learning ex. causes only a small change in the connection weights
What happens in connectionist networks?
-information about each concept is contained in distributed pattern of activity
-across a number of units
Is the operation of connectionist networks totally disrupted by damage?
what is graceful degradation?
disruption of performance occurs gradually as parts of the system are damaged
How can connectionist networks explain generlization of learning?
-similar concepts have similar patterns
-training a system to recognize the properties of one concept also provides info about other related concepts
How can different areas of the brain be specialized to process info about different categories?
1. double dissociation for categories
EX: "living things" and "nonliving things"
2. category specific memory impairment
What is the sensory-functional hypothesis?
-our ability to differentiate living things + artifacts depends on semantic memory system
-distinguishes sensory attributes + function
What does the Sensory-functional hypothesis predict about a patient who can't identify living things?
they should have impaired sensory abilities
What did Caramazza + Shelton find about the sensory functional hypothesis?
-reported a patient who couldn't identify living things
-impaired sensory memory
-also had impaired functional ability
(contradicts (S-F hypothesis)
What does the sensory-functional hypothesis predict about a person who can't identify artifacts
should have impaired functional knowledge
What did Ralphs find about the sensory functional hypothesis?
-reported a patient who couldn't recognize artifacts
-had impaired sensory ability
There are specific ____ in the brain for specific categories
How are neural circuits arranged in the brain for specific categories?
-distributed over a number of different cortical areas
Why might there be a limited number of categories that are innately determined?
because of their importance for survival
What did Wilmer et. al test?
-the idea that there may be a limited number of categories that are innately determined because of their importance for survival
How did Wilmer run his experiment?
-measuring face recognition ability in mozygotic + dizogotic twins
What were the results of Wilmer's facial recognition experiment?
-correlation of scores between identical twins was more than twice as high as the other group
-there may be a genetic basis for the mech involved in face recognition
What is the multiple factors approach?
-looks at how concepts are divided up within a category
-rather than identifying specific brain areas of networks for different concepts
Mechanical devices (EX: musical instruments) overlap with:
-artifacts (involve performing actions)
-animals (involve sound and motion)
How do mechanical devices have a widely distributed semantic representation?
-regions important for the representation of both living things and artifacts
patients may be able to identify mechanical devices even if _____
they perform poorly for other types of artifacts
What is another differentiating factor between animals and artifacts?
What is crowding?
when different concepts within a category share many properties
EX: "animals" all share "eyes," "legs," "ability to move"
-artifacts share fewer properties
Why might patients with category-specific impairments not have a category impairment at all?
-patients may have difficulty recognizing living things because they have difficulty distinguishing between items that share similar features
What is the embodied approach?
-our knowledge of concepts is based on reactivation of sensory + motor processes that occur when we interact with the object
What is an example of the embodied approach?
-when we use a hammer:
-different sensory areas are activated due to hammer's size/shape etc.
-motor areas are activated that are involved in carrying out actions involved in using a hammer
-interaction between action and perception
What are mirror neurons?
-neurons that fire when we do a task or when we observe another doing that same task
How do mirror neurons connect to the embodied approach?
-thinking about concepts causes activation of perceptual and motor areas associated with the concepts