Lesson 9

• Concept


  An idea about something that provides a means of understanding the world
• Concept


  • apple, redness, roundness, fruit
• Category


  A group of items into which different objects or concepts can be placed that belong together because they share some common features, or because they are all similar to a certain prototype
• Natural categories


  • Groupings that occur naturally in the world, like birds or trees
• Artifact categories


  • Groupings that are designed or invented by humans to serve particular purposes or functions, like automobiles and kitchen appliances
• Natural and artifact categories are relatively stable and people tend to agree on criteria for membership in them
• Ad hoc categories


  Categories created just for the moment or for a specific purpose, described not in words but rather in phrases, with content that varies depending on the context
• Basic level


  Concepts appear to have a basic level (sometimes termed a natural level) of specificity, a level within a hierarchy that is preferred to other levels
• Defining features


  Features that are necessary and sufficient to define a category, where each feature is an essential element of the category
• Prototype theory


  Grouping things together not by their defining features but rather by their similarity to an averaged model of the category, where a prototype is an abstract average of all the objects in the category we have encountered before
• Exemplars


  Typical representatives of a category, used instead of a single abstract prototype for categorizing a concept
• Objects appear to be recognized first in terms of their basic level, and only afterward are they classified in terms of higher- or lower-level categories
• People can categorize objects based on their own theories about those objects
• Semantic network


  A web of elements of meaning (nodes) that are connected with each other through labeled relationships
• Schemas are very similar to semantic networks, except that they are often more task-oriented
• Scripts


  Contain information about the particular order in which things occur, and include default values for the actors, the props, the setting, and the sequence of events expected to occur
• Production system


  Comprises the entire set of rules (productions) for executing a task or using a skill
• Production system


  • traffic-light red!
• ACT model


  A model of knowledge representation and information processing where procedural knowledge is represented in the form of production systems
• ACT-R model


  A model of information processing that integrates a network representation for declarative knowledge and a production-system representation for procedural knowledge
• In ACT-R, networks include images of objects and corresponding spatial configurations and relationships, as well as temporal information such as relationships involving the sequencing of actions, events, or the order in which items appear