Categorization and Prototypes

Family Resemblance in Categorization

• Cars as an example:

  • Expected features: four wheels, an engine (excluding electric), allows transportation from point A to point B.
  • Shared Resemblance: Cars generally share similarities. Most cars have headlights for safety.
  • Luxury Cars: Categorization is based on resemblance rather than a strict definition.
    • Features: Seat warmers or other features that designers consider defining of luxury.

The Problem with Definitional Approaches to Categorization

• Example: Defining a chair.
  • Initial Definitions: "Something you can sit on," "something that has a cushion," "something that has a backrest."
  • Limitations:
    • Variations: Different types of chairs (e.g., an inflatable chair, an abstract chair) may not fit the definition.
    • Specific Features: Specifying that a chair must have legs excludes chairs without legs.
    • Ambiguity: The function of an object can change its category (e.g., using a chair as a ladder).
    • Overlapping Categories: Defining a chair as something to sit on could include a table.
  • Conclusion: Definitional approaches are difficult because there are always exceptions.
    • Textbook Example: Figure 9.3 shows different types of chairs to illustrate this point.

Prototype Approach to Categorization

• Definition: A prototype is an average representation of a typical member of a category.

  • Typical Member: The most representative example of a category.

• Birds Example:

  • Typical Bird: A bird is generally thought of as something that has feathers and flies.
  • Characteristic Features: Typical members of a category share common features.

• Dogs Example:

  • Typical Dog: Most people think of is something that has four legs and likes meat.

• Past Encounters: Prototypes are usually based on past experiences and encounters.

  • Assumption: People have generally encountered common examples of a category.

• Penguins and Birds:

  • Atypical Examples: Penguins are birds, but they do not readily come to mind when one thinks of a typical bird.

High Prototypicality vs. Low Prototypicality

• High Prototypicality: A category member closely resembles the category prototype.

• Low Prototypicality: A category member does not closely resemble the category prototype.

  • Penguins: Penguins have low prototypicality within the category of birds.

• Categorization: The prototype approach categorizes based on what is most expected (high prototypicality) and what is least expected (low prototypicality).