L13 Categories - an introduction Flashcards
Where do we store our mental representations?
In our long-term memory
What is “concept formation”
How we build up concepts (mental representation)
What is the premise of the classic view of concept formation?
That categories are defined by the presence or absence of specific properties.
- Categories have defining properties*
- If they have these properties it is sufficient to classify the object as being in the category*
Categorizing a square as being defined by having four sides of equal length and all inner angles are equal is which view of concept formation?
The Classic View of Concept Formation
e.g. it needs these properties to be a square (has defining properties)
The classic view states the categories are defined by necessary and sufficient features.
What is meant by necessity and sufficiency?
Necessity: If any of these features are missing, it is definitely not a member of this category
Sufficiency: If all of them are present, then it is definitely a member of this category
The classic view of concept formation believes that there are in-between cases within a category
True or False
False
They are either “in” a category or “not”, you cannot be half-in
- If the necessity and sufficiency characteristics are met, then there are no in-between cases.*
- All members of a category are equal because they all have the necessary and sufficient features to be in the category*
In the classic view of concept formation, every member of a category is considered to be an equally representative member of the category as all other members of the category.
True or False
True
As they all share the same necessary and sufficient qualities, they are all equally representative of the category
What are the 3 main claims for the classical view of concept formation
- Concepts are mentally represented as definitions. A definition provides characteristics that are necessary and jointly sufficient for membership of that category
- Every object is either in or not in a given category, there are no in-between cases
- Every member of a category is considered to be an equally representative member of the category as all other members of the category
Do objects neatly fall into a binary category membership?
No
Objects fit into all types of categories
Are objects equal in terms of their representativness within a category?
No
A small bird is more representative of “birds” than an emu or penguin which cant fly, even though they are birds
How did Hampton (1979) test for binary category membership?
Could objects be “in between” categories
Presented participants with a list of potential members of 8 categories and asked them to rate their membership on 7 point scale
- Category membership ratings formed a continuum ranging from 0 to 100%
What were the results of the Hampton (1979) binary category membership experiment?
Some category members were always included or excluded, others were borderline cases
Categories are not binary
In the Hampton (1979) experiment, the results could have been due to different people having different conceptual representations.
How did McCloskey and Glucksberg (1978) demonstrate that even individuals change their inclusion criteria over time?
Asked participants to make repeated category judgements in two different times (time A and time B)
Results: for 22% of borderline cases, the participants changed their minds
Conclusion: category membership is not binary
What did Rosch (1975) test in his experiment?
The “typicality” of members of 10 different categories
What was the result of the Rosch (1975) experiment?
Were these results reliable?
Typicality differs across category members
Very reliable: inter-rater reliability of r = .97
intuition consistent across individuals
How did Rosch and Mervis (1975) test the family resemblance theory?
20 exemplars (category members) from 6 different categories
• One group of participants rated the typicality of the
exemplars (how typical is X as a member of category Y)
• Another group generated features for the exemplars (X
has the feature )
• A third group rated the applicability of the features in
relation to each of the exemplars the feature
( is applicable to X, M, C, T, A & B)
What does this show us about category membership?
Some features are more important in order to belong into a certain category than others
How did Rosch and Mervis (1975) get their family resemblance statistic
Family Resemblance is a weighted sum of featural overlap amongst category members
e.g. see how many menbers fit the definition, summed that number and then added the summed number to the members of that category in order to get family resemblance - this gave them the F.R number
What was the important finding about features relating to a category that was foudn in the Rosch and Mervis (1975) experiment
The features generated by participants only applied to a small subset of the category members - very few applied to all of the members
None of the features could be described as necessary and sufficient
Disproves classical view
These are the statements of the classic view, what does empirical evidence suggest instead?
- Concepts are mentally represented as definitions. A definition provides characteristics that are necessary and jointly sufficient for membership of that category.
- Every object is either in or not in a given category, there are no in between cases.
- Every member of a category is considered to be an equally representative member of the category as all other members of the category.*
- Concepts are mentally represented as definitions. A definition provides characteristics that are necessary and jointly sufficient for membership of that category.
