Categorization and Classification

Categorization:

e.g.

 

 

 

 

 

 

 

Similarity:

The Hierarchical Organization of Categories:

1.Superordinate categories:

e.g. Furniture

Furniture: tables, chairs, beds, lamps, etc

 

a)

2. Basic-level categories:

e.g. table

a)

b)

c)

3. Subordinate categories:

e.g. coffee tables vs. dining room tables.

 

a)

Different Views on category structure:

A. The Classical View:

e.g. "triangle"

 

 

 

1.

2.

e.g.

Problem:

 

 

 

 

B. The Probabilistic View:

e.g.

 

 

 

1.

 

 

 

 

2.

Typicality:

 

more typical items are those that:

a)

 

 

 

b)

 

 

 

e.g.

 

 

Categorizing Novel Patterns:

1. Nearest-neighbor rule -

Problems:

1)

 

 

 

2)

 

 

 

2. Average distance rule -

Advantage:

1)

 

 

 

 

Problems:

1)

 

 

3. Feature frequency rule -

Disadvantage:

1)

 

 

4. Prototype rule -

Advantage:

1)

 

 

 

 

 

 

Problems:

1)

 

 

 

 

 

 

 

 

 

 

2)

 

 

 

 

 

e.g.

 

 

 

 

 

 

 

 

3)

 

 

 

 

 

 

 

 

 

 

Evidence in Support of Prototype View:

 

1)

 

 

 

 

 

2)

 

 

 

5. Exemplar View-

•  

 

 

 

 

 

 

 

•  

 

 

 

 

 

•  

 

 

 

 

 

•  

 

 

 

 

Evidence in Support of Exemplar View:

 

1)

 

 

 

 

 

 

 

2)

 

 

 

 

e.g.

 

 

 

 

 

 

Problems with Exemplar View:

1)

 

 

 

 

 

2)

 

 

 

 

 

How do we determine "Similarity"?

Tversky's Contrast Model of Similarity (1977):

BUT 1st

What is a Model????

Formal Model:

•  

 

 

 

 

 

•  

 

 

 

 

 

•  

 

 

 

 

 

General Formal Model Testing:

 

 

 

 

 

 

Contrast Models with a narrative or verbal approach to theory building.

 

e.g.

 

 

 

 

A formal model of similarity: Tversky's Contrast Model of Similarity (1977)-

 

•  

 

 

 

 

 

 

 

 

Symbols:

a=

b=

s=

A=

B=

⁼

A-B=

B-A=

 

• Prediction of Model:

 

 

f =

q, a, and b=

 

 

e.g.