Chapter 9 - Conceptual Knowledge Flashcards
Conceptual Knowledge
knowledge that enables us to recognise objects and events and to make inferences about their properties
-Concept:
mental representation used for a variety of cognitive functions
categories of objects, events and abstract ideas
-Categorization:
is the process by which things are placed into groups called categories
-categories are all possible examples of a particular concept
category
includes all possible examples of a concept
Why categories are useful?
- help to understand cases not previously encountered
- “Pointers to knowledge”
- categories provide a wealth of general information about an item
- allow us to identify the special characteristics of a particular item
Definitional approach to categorization
we can decide whether something is a member of a category by determining whether a particular object meets the definition of the category
- Does not work well
- Not all members of everyday categories have the same defining features
Family resemblance
refers to the idea that things in a particular category resemble one another in a number of ways
prototype approach to categorization
membership to category is determined by comparing the object to a prototype that represents a category
- characteristic features that describe what members of that concept are like
- An average of category member encounters in the past
Prototype
a “typical” member of the category
Typicality
high typicality means that a category member closely resembles the prototype, low means opposite
Determining Categories by Similarity
- compare object to a “standard”
- prototype approach: the standard is determined by averaging category members
- exemplar approach: the standard is created by considering a number of typical members of a category
Exemplar approach
the standard is created by considering a number of typical members of a category
COGLAB: Prototype
- What methods did we employ in this experiment?
- On each trial you were shown a dot pattern and were asked to classify it as belonging to Category A or Category B. You were asked to respond as quickly and as accurately as you could.
- In the training phase (60 trials if all are finished correctly), each dot pattern was a variation of one of two fixed prototype random dot patterns. The variations are made by randomly taking ten of the twenty-five dots in a prototype and moving them to a new position.
- In the test phase, a new set of dot patterns was presented. The dot patterns in the testing phase were of four types. One was the prototype that corresponds to the A category. Another was the prototype that corresponds to the B category. The other two patterns were new variations of these prototypes (one variation for each prototype).
- Average reaction times for previously unseen prototypes and previously unseen variations of the prototypes.
- The expected effect is that the RT for the prototypes is smaller
Posner & Keele (1968)
- Stimulus: Dot patterns (3 different prototypes that were constructed by placing dots in nine randomly selected positions in a 30X30 matrix)
- Participants see 4 distortions of each prototype and changed until they could discriminate them
- Learn to categorize patterns with feedback
Results
• Prototypes are categorized as well as old distortions
• Both are categorized better than new distortions
• The new, far-removed distortions are least well categorized
-Prototypes are explicitly extracted from examples and serve as representation for category
strong positive relationships exisits between
prototypicality and family resemblance
-When items have a l arge amount of overlap with characteristics of other items in the category
the family resemblances of these items is high
Low overlap =
low family resemblance
To measure the family resemblance (Rosch & Mervis, 1975)
- List the characters of the following items
- Chair Sofa Mirror Telephone
-Results
- Chair Sofa share a lot of common characteristics
- Mirror Telephone share few common characteristics
- High family resemblance corresponding to high prototypicality (chair)
- Low family resemblance corresponding to low prototypicality (Telephone)
Sentence verification technique
used to determine how rapidly people could answer questions about something’s category - “an apple is a fruit”
faster for words with high typicality
typicality effect
ability to judge highly prototypical objects more rapidly
high prototypical objects are judged
more rapidly
-Rosch (1975b)
- Hearing “green” primes a highly prototypical “green”
- Prototypical objects are named first (Mervis et al., 1976)
- Please list the birds you know as many as possible
Priming
occurs when a presentation of one stimulus facilitates the response to another stimulus that usually follows closely in time
Naming
people are more likely to list some objects than others when asked to name objects in a category
exemplar approach to categorization
involves determining an object is similar to other objects, does not include a single “average” but involves many examples called exemplars
Exemplars
are actual members of that category that a person has encountered in the past (standard)
Exemplar is similar to prototype in that
representing a category is not defining it
Exemplar is different to prototype in that
representation is not abstract
-descriptions of specific examples
-the more similar a specific exemplar is to a known category member
the faster it will be categorized (family resemblance effect)