Categorization Review Sheet Answers

Answer the following questions in the space provided.

1. Define categorization.

Categorization occurs when we group things together as a category that gives us the ability to label those items as being the same word.

2. Why is categorization very useful?

• Accessing a particular word, you gain access to lots of information about what that word refers to.
• Categories allow us to predict information (without them we would have to treat each new instance as if it were one of a kind).
• Categories also allow us to communicate (when I say "classroom" you all know what I am talking about).
  

3. Name the 3 different kinds of categorization.

• Classical
• Prototype
• Exemplar

4. Are categories a language skill or a cognitive skill?

Cognitive. However, they do underlie a lot of language, and so they are clearly relevant to understanding language at the level of the word.

5. What is the classical approach to categorization based on and what are the problems with this approach?

Based on defining features.
Problems:

• Hard to come up with defining features.
• Typicality Effects. Some examples seem better representations of category than others even when they share all the features of that category. This was tested with reaction times in subjects.
• There are instances were subjects have trouble deciding on whether something is a member of a category and even change their mind from time to time.
• Can't handle disjunctive categories. So, in baseball, you can have a strike in 3 different instances.
• Subjects list unnecessary features of categories.
• Nested Concepts. X is a member of Y and Y is a member of Z. X has to meet the defining features of Z too but you are faster to identify x as a member of Y that as a member of Z. e.g Faster to recognize a robin as a bird than as an animal.

6. What is the prototype theory of categorization based on?

This is based on features that are salient and probabilistic (something which is often true). Typical or likely features. Items classified not on the basis of whether their features match but on the basis of their similarities to the prototype. The more features the item has in common with the prototype, the greater the likelihood it will be classified as part of that category, but no single feature is necessary.

7. How is the exemplar approach to categorization different than the prototype approach?

Here, every instance of a category is stored in memory, and are called exemplars. Unlike the prototype theory, there is no pre-stored prototype. Items are classified on the basis of their similarity to stored exemplars. So, in order to decide if something is a member of a category, you retrieve some of the exemplars, and then either :

• determine similarity to all retrieved exemplars and compute average similarity
• compute similarity to nearest (most similar) exemplar (nearest neighbor rule)