Lecture 16: Knowledge 16 Flashcards
According to the theory: Classical view, how do we represent concepts
Intuition: Concepts have definitions, a list of necessary and sufficient conditions for membership in a category. Concepts can be defined in terms of individually necessary and jointly sufficient features
Ex: a square: closed figure, four sides and corner, equal side lengths and equal angles.
Bachelor: Adult, unmarried, male (wrong)
According to the theory: Prototype view, how do we represent concepts
Concepts do not have definitions. They are represented by a prototype. Other members share a family resemblance relation to the prototype, and typicality is a function of similarity to the prototype.
According to the theory: Exemplar model, how do we represent concepts
Concepts do not have definitions or summary representations. A concept is the set of all examples of the concept that are stored in memory.
Exp: Concept bird: all exemplars of birds in memory.
In what ways are basic Level categories special
Basic level names are used to identify objects, they are moderately specific. Privileged level of categorization: bird, screwdriver, chair. ppl list many common attributes at the basic level.
Category
a group of objects in the world
Concept
a mental representation of a group of objects
Categorization
to think of an object X as an instance of a category
Why we love the classical view
- cognitive economy = just need definition
- generalization = must have necessary features
- communication = everyone has same concept
Why do we hate the classical view
- failure to find definitions for real-world concepts (e.g., game, bachelor)
- borderline cases (e.g., is a lamp/rug furniture?)
- some members are better than others (e.g., 3 is a “better” prime # than 2, robins are “better” birds than penguins) AKA typicality effects
Typicality effects
phenomena in which some examples seem like “better” category members than others
typicality predicts a variety of behavioral measures:
- RT to identify picture/word as category member –> fast for best, slow for worse
- generalization: lions express protein X, what about whales? (high prob) vs. whales express protein X, what about lions? (low prob); more likely to go from typical –> atypical
Prototype view
1 of 3 theories on how we represent concepts; concepts do not have definitions, they are represented by a prototype; other members share a family resemblance relation to the prototype, and typicality is a function of similarity to the prototype
prototype maximizes average similarity
graded membership
Family resemblance
the notion that members of a category (e.g., all dogs, all games) resemble each other; in general, relies on some number of features being shared by any group of category members, even though these features may not be shared by all members of the category; therefore, the basis for family resemblance may shift from one subset of the category to another
Graded membership
the idea that some members of a category are “better” members and therefore are more firmly in the category than other memebrs
Posner & Keele’s study
evidence for prototype view
see dot patterns, judge whether each belongs to category A or B –> guess at first, but will get better with feedback; then show old, new, and prototype (new) dot patterns and judge whether you had seen it before
results: prototypes were judged to be familiar, categorized as much as “old” even though they were new
–> automatic abstraction of prototypes
Exemplar Model
1 of 3 theories on how we represent concepts; concepts do not have definitions or summary representations; a concept is the set of all examples of the concept that are stored in memory (e.g., concept bird: all exemplars of bird in memory)
Superordinate category
general categories: animal, tool, furniture
Basic Level category
moderately specific, privileged level of categorization: bird, screwdriver, chair
has special status; names used to identify objects; members tend to be visually similar; children use basic-level categories first
members in these categories have many attributes in common: people list many common attributes at the basic-level, few at the superordinate level, about the same for basic-level and subordinate-level
subordinate category
specific categories: humming bird, Phillips screwdriver, rocking chair (expert level)
Number system: small exact
On infants, They know the EXACT quantity but is limited to set size of 3. stil works when all items are occluded (close). Attentional tracking system.
Language: She has 2 sisters.
Number system: large approximate
In infants, they know approximate quatity: 16>8, 32>16, but fails 12 vs. 8, 24 vs. 16. Its imprecise: 2:1 ratio. Doesnt work when things are occluded (close). Approximate magnitude system.
Language: She thought hundreds of students.
Number system: large exact
1 of 3 number systems; only one that’s language specific. Only one from the three number systems that was dependent on the native language of learning.
example = She lost 9 treasure chests
Number sense in animals
Animals have it. example rat study.
Number sense in children
spontaneous emergence in young children. small children 3/4 dont have number concepts. 3/4 yr olds question why they are being asked a second time the same question, so they look for alternative ways to satisfy adult. but when asked which one they prefer to eat, they always chose the bigger one.
Number sense in adults
Similar task as given to children (one dot pattern, then another: same number of dots?) Adults are more accurate than rats, but are also error-prone: errors and variability increase at larger target numbers.
Verbal number system tied to the language of one’s original arithmetic learning
Mechner’s rat accountant basic findings
rule of the game: lever B is connected with food, first press A a desired # of times then press B once for food; if pressed B too early, got penalty (shock)
found: rats do possess rudimentary # sense; precision declines when desired # increases
objections: # of times the lever is pressed or time elapsed since the beginning of a trial?
dealing with objections: Mechner & Guerrekian varied the degree of food deprivation; hungrier rats pressed levers faster, this should affect time elapsed, but they still pressed the same # of times
Mechner’s rat accountant
number vs. elapsed time
hungrier rats pressed level faster: this should affect time elapsed, but they still pressed the same # of times.
What is the cross-modal number sense?
Experiment done by Mech and Church. When the rats were presented with 2 tones plus 2 flashes, it didnt evoke an even greater sensation of “two=ness.” They became 4. Truly abstract number sense: Rats can add
