I．Categorization

1. Definition

Categorization refers to the process by which people use language to classify the world around and inside them. It is fundamental to human cognition. 

In the past two decades cognitive psychologists and cognitive linguistics have gained new insights into the nature of categories.

II. Prototypes

1. Definition

A prototype is a set that has typical, central features. Others are peripheral features, which are not typical but related.

2. The classical theory and the prototype theory

The classical theory of concepts is to define category by using sets of necessary and sufficient conditions. All members of categories are equal, and the boundaries of categories are clear.

The theory of prototype is proposed by Eleanor Rosch. Some members of a category are typical while others are peripheral. A concept is centered round by a representation of an ideal example or prototype. Whether something belongs to a category and hoe central it is are determined by its degree of resemblance to the prototype.

The main difference between the classic theory and the prototype theory:

(1) The set of prototype features does not constitute a definition, as the features are not individually necessary.

(2) Members of a category do not all have the same status: experimental subjects judge some members of a category to be “better examples”.

(3) The fact that not all members have to be satisfied means two members of a category may resemble the prototype in different ways and as a consequence may have little resemblance to one another.

III. Hierarchies

Definition: Conceptual network

Type:

(1) One type of hierarchy is hyponymy. The network is composed of three levels of hierarchies: a superordinate level, a basic level, and a subordinate level. The lower the level, the more features, and therefore the more specific. The basic level is identified as cognitively most important, because the level is used most frequently in daily life.

(2) Another type of lexical hierarchy is meronymy, in which the vertical relation is meronymy and the horizontal relation is co-meronymy. It illustrates a portion of a part-whole hierarchy.