cognitive psychology

1. THE KNOWLEDGE- BASED VIEW OF
CONCEPTS AND CATEGORIZATION

2. • People’s knowledge and worldview
• Murphy and Medin-
Relationship between concept and examples –
analogous to that between theory and supporting data.
• to justify the classification and to explain why certain instances happen to go together
• an apparently disparate collection of objects - a coherent category in particular
circumstances.

3. • Barsalou(1983)-
• Category- children, pets, photo albums, family heirlooms and cash
• a fire is about to engulf a house- “things to save”.
• Goldfish isn’t a particularly prototypic pet or fish. (Hampton,2007;Wu and
Barslou,2009)

4. • Other approaches-fail to answer -how things in the same category go together.
• people’s theories or mental explanations about the world are intertwined with their
concepts and provide the basis for categorization. (Heit,1997)
• It allows explaining -
1. the instances that go together and why
2. the features and aspects of instances that are important and why
3. the features and aspects that are irrelevant and why

5. • Medin(1989), based on work by Hilary Putnam(1975)
• examined people’s reliance on underlying nature as a basis of many concepts.
• Psychological essentialism
1. objects, people, or events have certain essences
• Essence limits the kinds of variation that different instances of a category
can show.

6. • connect deeper properties to superficial properties.
• Medin (1989)- the categories male and female
• May sometimes make error, but correct most of the time.

7. • People’s knowledge of the essence of a category varies by level of expertise.
• Biologists, know a lot more about the genetic structure than do laypeople.
• Experts make different and more accurate classification.
• Medin’s (1989) idea is that classifying on the basis of perceptual or other superficial
similarity may be effective strategy.
• People classify on the basis of deeper principles.
• People’s classification will change as they become more experience and
knowledgeable.

8. • The way people acquire and mentally represent may also vary as a function of what
the concepts are(Murphy,2005).
• Kinds of concepts-
1. Nominal kind concepts
2. Natural kind concepts
3. Artifacts concepts

9. 1.Nominal kind concepts-
• have clear definitions.
• Include information about necessary and sufficient features.
2.Natural kind concepts-
• are things naturally occurring in some environment
• Include information about definitional or essential features, especially about molecular and
chromosomal structure.
• Have family resemblance structure but equally well explained within a knowledge based
approach.
3.Artifacts concepts-
• Things constructed to serve some function or accomplish some task.
• Highlight information about the object’s purpose or function and may be adequately
described only within the knowledge based approach.

10. • Barton and Komatsu (1989)-
• Presented participants with five natural kind concepts (goat, water, gold).
• Five artifacts (tv, pencil, mirror).
• Asked to imagine transformation- some were phrased in terms of function or purpose
others were in terms of physical features and third type in change was molecular.
• Result- In natural kind Ps were most sensitive to molecular transformations and In artifacts
most sensitive to functional changes.
• All concepts are not treated equally.

11. Five approaches to conceptual structure  categorized into 2 major types
Similarity based category
Classical , prototype &
exemplar views
Categorization based
on the similarity of an
instance  abstract
specification of the
category or to one or
more exemplars.
Explanation based
category (Komatsu,1992)
Schemata/ scripts view
& some knowledge
based view
Classification based
on the meaningful
relationships among
instances and
categories.

12.  Goodman  term similarity is pretty empty without some specification of what the
relevant respects are.
 The contrast between similarity-based and explanation-based approach :
 Degree to which people focus on superficial, perceptual information about a particular
object
Versus
 Degree to which they focus on deeper, knowledge – derived information about an
objects function or role.

13. The five approaches to concepts differ on several dimensions.
 Cognitive economy of the mental representation
• Idea is to save on mental resources by limiting the amount of information we must store.
 Informativeness of the category.
 So, any theory of concepts and categorization must STRIKE A BALANCE between cognitive
economy and informativeness.
 Any theory of concepts must explain a concept or category’s coherence.

14.  Workers in artificial intelligence – discovering – that a truly intelligent program or
system must have
• a wide or deep knowledge base and
• must be able not only to store but also retrieve a great deal of information to the world.
 Proponents of knowledge based view of concepts hold that people use their own theories to
guide their classification of objects.
 Experts have more elaborated theories and therefore different mental representation
than do novices.

15. Organizing
knowledge
Network
Models
ACT Models
Connectionist
Models

16. Forming Concepts and
Categorizing New
Instances
The Classical
View
The Prototype
View
The Exemplar
View
The Schemata /
Scripts View
The
Knowledge-
Based View

17. THANK YOU! 