cognitive psychology report

REPRESENTATION and ORGANIZATION of KNOWLEDGE in MEMORY:

Concepts, Categories, Networks and Schemas



1. How are representations of words and symbols organized in the mind?

2. How do we represent other forms of knowledge in the mind?

3. How does declarative knowledge interact with procedural knowledge?

INTRODUCTION



ORGANIZATION OF

DECLARATIVE KNOWLEDGE



ORGANIZATION OF DECLARATIVE KNOWLEDGE

-CONCEPT – the fundamental unit of symbolic knowledge (knowledge of correspondence between symbols and their meaning for example, that symbol “3” means three), an idea about something that provides a means of understanding the world.

-CATEGORY-is 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 similar to a certain

prototype.



ORGANIZATION OF DECLARATIVE KNOWLEDGEConcepts and Categories

Concepts and categories can be divided in various ways:

NATURAL CATEGORIES

ARTIFACT CATEGORIES

are groupings that occur naturally in the world like birds or tree.

are groupings that are designed or invented by humans to serve particular purposes or functions.

Natural and Artifact Categories are relatively stable and people tend to agree on criteria for membership.




On the contrary..

-CONCEPTS-are not always stable but can change. They are described not in words but rather in phrases.

they also appear to have a basic level (sometimes

termed as a natural level) of specificity, a

level within a hierarchy that is preferred to other

levels.




In general, the basic level is neither the most

abstract nor the most specific. This basic level can be manipulated by context or expertise.




The basic level is the one that most people find to be maximally distinctive. By means of training, the

basic level can be shifted to a more subordinate level.

For example, the more a person learns about cars, the more he or she is likely to make elaborate

distinction among cars.

Research suggests that the difference between experts and novices are not due to qualitative

mechanisms but rather quantitative differences in processing efficacy.




So, how do we decide what objects to put into

a category?




-FEATURE-BASED CATEGORIES

-PROTOTYPE THEORY

-THEORY BASED VIEW OF CATEGORIZATION

-SEMANTIC-NETWORK MODELS

-SCHEMATIC REPRESENTATIONS




FEATURE-BASED CATEGORIES: A DEFINING VIEW

the classic view of categories disassembles a concept into a set of featural components. All those features are then necessary (and sufficient) to define the category. This means that each feature is an essential element of the category. Together, the features uniquely define the category; they are defining features.

For a thing to be an X, it must have that feature. Otherwise it is not an “X”.




BACHELOR

MALE

UNMARRIED

ADULT




WIFE

FEMALE

MARRIED

ADULT




The Problem:

1. Some categories do not readily lend themselves to featural analysis.

2. A violation of those defining features does not seem to change the category we use to define them.




In sum, the feature-based theory has some attractive

features, but it does not give a complete account of

categories.




PROTOTYPE THEORY: A CHARACTERISTIC VIEW

grouping things together not by their defining features rather by their similarity to an averaged model of the category.

PROTOTYPEis an abstract average of all the objects the category we have encountered before

CHARACTERISTIC FEATURE

describe (characterize or typify) prototype but are not

necessary for it.




So what exactly is a characteristic feature?

whereas a defining feature is shared by every single object in a category, a characteristic feature need not to be Instead, many or most instances possess each character feature..




Psychologists differentiate two kinds of categories: Classical concepts and Fuzzy Concepts.

CLASSICAL CONCEPTS FUZZY CONCEPTS

- Can be readily defined through defining features

- May be built on defining features

- Cannot be so easily defined

- Built around prototypes




Real-World Examples: Using ExemplarsSome Psychologists suggests that

instead of using a single abstract prototype for categorizing a concept, we use multiple, specific exemplars.

EXEMPLARS are typical representatives of a category

In particular, categories are set up by creating a rule and then by storing examples as exemplars. Objects are then compared to the exemplars to decide whether or not they belong in the category the exemplars represent.




A SYNTHESIS: COMBINING FEATURE-BASED and PROTOTYPE THEORIIES

A full theory of categorization can combine both defining and characteristic features, so that each category has both prototype and a CORE.

CORE refers to the defining features something must have to be considered an example of category.

The prototype encompasses the characteristic features that tend to be typical of an example but that are not necessary for being considered as an example.

The core requires that someone labeled as a robber be a person who takes things from others without permission. The prototype, however, tends to identify particular people as more likely to be robbers.




“ROBBER”




A departure from feature-based, prototype-based, and exemplar-

based views of meaning is a THEORY BASED VIEW of meaning

also sometimes called an EXPLANATION-BASED VIEW.




HOW DO PEOPLE USE THEIR THEORIES FOR

CATEGORIZATION?




A THEORY BASED VIEW OF MEANING hold that people understand and categorize concepts in terms of implicit theories, or general ideas they have regarding those concepts.

For example, what makes a GOOD SPORT?




In the PROTOTYPE VIEW, you would try to find characteristic features of a good sport.

In the COMPONENTIAL VIEW, you would try to isolate features of a good sport.

In the EXAMPLAR VIEW, you might try to find some good examples you have known in your life.




In the theory-based view, you would use your experience to construct an explanation for what makes someone a good

sport.




SO what does it means to be a GOOD SPORT in a theory-based view?

A good sport is someone who, when he or she wins, is gracious in victory and dos not mock losers or otherwise make them feel bad about losing. It is also someone who, when he or she loses, loses graciously and does not blame the

winner, the referee, or find excuses. Rather, he or she takes the defeat in stride, congratulates the

winner, and then moves on.




FINDING THE “ESSENCE” OF THINGS

to be continued…




SEMANTIC-NETWORK MODELS

Semantic Network Models suggests that knowledge is represented in our minds in the

form of concepts that are connected with each other in a web-like form




Collins and Quillan’s Network ModelsKnowledge is represented in terms of hierarchal

semantic network.

A SEMANTIC NETWORK is a web of elements of meaning (nodes) that are connected with

each other through links.




ORGANIZED KNOWLEDGE representation takes the form of a hierarchal tree diagram. The elements are called nodes they are typically concepts.

The connections between the nodes are labeled relationships. They may indicate category membership, attributes, or some other semantic relationship. Thus a network provides a means of organizing concepts.




INHERITANCE

This concept implies that lower-level items inherit the properties of higher-level items.

Whatever was known about items at higher levels in a

hierarchy was applied to all items at lower levels in the

hierarchy




COMPARISON OF SEMANTIC FEATURES

Knowledge is organized based on a comparison of semantic features, rather than on a strict hierarchy of concepts

cognitive psychology report

Education

categories concepts

categories feature

categories theproblem

categories thebasic

changethe category

subordinate level

procedural knowledge

forms of knowledge