PSYB57H3 Chapter Notes - Chapter 8: Ludwig Wittgenstein, Eleanor Rosch, Exemplar Theory
Chapter 8: Concepts and Generic Knowledge
•You need concepts in order to have knowledge, and knowledge in order to function
Definitions: What Is a “Dog”?
•One possibility is that you know something akin to a dictionary definition; however Ludwig Wittgenstein
argued that the simple terms we all use every day actually don’t have definitions
•What is a “game”? There is a big difference between hide-and-seek and the Olympic Games
•What is a “shoe”? What about a shoe filled with cement, that cannot be worn?
Family Resemblance
•We can say that a dog usually has four legs and usually barks, but this allows a degree of uncertainty
and some exceptions to the rule
•Wittgenstein proposed that members of a category have a family resemblance to each other: many
features shared among the instances of the concept, but no features shared by all of the instances
•One way to think about this pattern is by thinking of an “ideal”—someone who has all of the family’s
features, each member of the family has some features in common with this ideal, and therefore some
features in common with other family members
•We can identify “characteristic features”—features that many category members have
Prototypes and Typicality Effects - Eleanor Rosch mid 1970’s
•Definitions may set boundaries: if a test case has certain attributes, it’s inside the boundaries
•In contrast with this is the prototype theory: perhaps the best way to identify a category is to specify
the “center” of the category, rather than the boundaries
•A prototype is an average of what has been seen, and in some cases, literally the ideal for the category
•Different people may have different prototypes
•The prototype will serve as the benchmark, and reasoning is done with reference to the prototype
•Membership in the category is not a “yes” or “no” decision; instead it’s “more” or “less”; graded
membership: objects closer to prototype are better members of the category than those farther from it
Testing the Prototype Notion
•Sentence verification task: participants shown sentences and they decide whether they are true or
false; most experiments are interested in how quickly participants can do this task. Their speed of
response varies from item to item in a category
•According to the prototype perspective, participants make these judgements by comparing to the
prototype and take less time if the item is more similar to the prototype
•Production task: e.g., name as many birds or dogs as they can; prototype and birds closer to
prototype mentioned first; people think of prototype and what resembles it
•Rating tasks: e.g., which birds are “birdier”; birds closer to the prototype are rated “birdier”
Basic-Level Categories
•Certain types of categories are also privileged—in their structure and how they are used; you would
more likely say “chair” rather than “piece of furniture” or “upholstered armchair”
•Basic-level categorization: there is a “natural” level of categorization, neither too specific nor to
general, that you tend to use in your conversations and reasoning; basic level categories are usually
single words, while more specific “subordinate” categories are phrases
Exemplars
•Prototype theory isn’t the only way you can think about data
•Typical category members are often found more attractive
Analogies From Remembered Exemplars
•Exemplar-based reasoning: an exemplar being defined as a specific remembered instance rather than
general
