1 / 14

Categorization

Categorization. Concepts and Categorization. Concepts allow for efficient categorization But, how are concepts represented ? What “defines” an object? Primary qualities Secondary qualities How do we decide ‘object X’ belongs with ‘category Y’?. Natural Levels of Categorization.

jalila
Download Presentation

Categorization

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Categorization

  2. Concepts and Categorization • Concepts allow for efficient categorization • But, how are concepts represented? • What “defines” an object? • Primary qualities • Secondary qualities • How do we decide ‘object X’ belongs with ‘category Y’?

  3. Natural Levels of Categorization • Rosh et al.’s (1976) three “levels” of categorization • Superordinate level • Basic level • Subordinate level

  4. Natural Levels of Classification • Rosh et al. (1976) • Presented subjects with category labels • Subjects named as many features in common to all members of the given category label

  5. Natural Levels of Classification • Rosh et al. (1976) • Examined number of attributes at each category level • “Best” level of categorization is basic level • Why not superordinate level? • Why not subordinate level?

  6. Natural Levels of Classification • Rosh et al. (1976) basic level category “models”

  7. Tanaka and Taylor (1991) • Expertise guides classification • What is this? • And this? Vehicle (or Ship) v Starship v Ambassador Class Vehicle (or Ship) v RomulanWarbird v D’deridex Class

  8. Tanaka and Taylor (1991) • Bird experts vs. dog experts • Subjects identified pictures of specific birds and dogs (subordinate-level) or common birds and dogs (basic-level)

  9. Tanaka and Taylor (1991) • Expertise sped responses subordinate exemplars, and non-experts faster at basic level exemplars

  10. Categorization • OK, so how do we actually categorize? • Definitional approach • Compare features of item defining characteristics for categories • Problem is what defines a defining characteristic? • Nearest-neighbor rule • Select the category containing an item that is most similar to the item to be classified • Average distance rule • Select the category containing items that have the greatest average similarity to the item to be classified • Prototype rule…

  11. Category: Birds Bat (6.15) Penguin (4.53) Owl (2.96) Sparrow (1.18) 7 6 5 4 3 2 1 Low (Proto)Typicality High Typicality • Objects may be classified by comparison to prototypes • Rosch (1976) found objects differ in typicality • High prototypicality • Low prototypicality

  12. Typicality • Items are listed in order of typicality under each superodrinate category

  13. Typicality • Basic level category “models” may be prototypes

  14. Typicality • Smith, Shoben and Rips (1974) • Sentence verification task • Typicality effect

More Related