Introduction to Cognitive Science

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Feb 23, 2014 (3 years and 7 months ago)

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COGN1001

Introduction to
Cognitive Science

Sept 2006 :: Lecture #1 :: Joe Lau :: Philosophy HKU


Please write this down



http://philosophy.hku.hk/courses/200607/cogn1001

Topics


About this course


What is cognitive science?


The computer model of the mind

About this course

About this course


Course coordinator


Other teachers


Course tutor


Assessment


60% 2
-
hour final exam.


25% 5 problem sets; one for each topic.


10% tutorial participation.


5% tutorial attendance.

What is

cognitive science?

Longuet
-
Higgins, H.C. (1973) Comments on the Lighthill report. Artificial
Intelligence
-

A Paper Symposium. London: Science Research Council.

By 1960 it was clear that something interdisciplinary was
happening. At Harvard we called it cognitive studies, at Carnegie
-
Mellon they called in information
-
processing psychology, and at
La Jolla they called it cognitive science.


George Miller.

What is cognitive science?

Cognitive science is

the
science

of
mind and behavior
.

How is it different

from psychology?


Cognitive



Of or pertaining to cognition, or
to the action or process of
knowing (OED)


Understanding knowledge
acquisition and use is the key
to understanding the mind.

Colorless green ideas sleep furiously.

So what is cognitive science?


Cognitive science is a scientific study of the
mind with special emphasis on the use and
acquisition of knowledge and information.


Implications


An inter
-
disciplinary approach


Many scientific
disciplines contribute to cognitive science.


A computational approach


Explain information
processing in terms of neural computations.

Information processing everywhere


Perception


acquiring real
-
time information about the surrounding
environment.


Language use


making use of information about syntax, semantics and
phonology.


Reasoning


combining different sources of information, deriving new
information, testing consistency of information, etc.


Action


making use of information in action planning and guidance.


Memory


storing and retrieving information


This is one reason why cognitive science is inter
-
disciplinary.

Explaining information processing


What is the best explanation of why a system is
capable of complex information processing?


Answer: The system is a computer.

Why there was no cognitive science


They didn’t think that knowledge is the key.


Perhaps it is a special substance? (Dualism)


Perhaps it is stimulus
-
response? (Behaviorism)


They didn’t know about computers.


Small stupid steps combine to do difficult things.

A useful short history:


http://ls.berkeley.edu/ugis/cogsci/major/about.php

VIP #1


Cognitive science

is about

how the mind

processes
information
.

What is special about cognitive
science?


Focuses on knowledge and information as
the key to understanding the mind.


Interdisciplinary


Computational approach


Special relevance to IT and AI


Individualistic


Multi
-
level explanations

Social psychology

Educational psychology

Psychology

Cognitive science

More on the

computer model of the mind

Quiz: What is a computer?

(a) A person

(b) A machine

What is computation?


Rule
-
based manipulation of symbols.

17x11=?


170


17

187

S = str_replace( “cat” , ”c” , ”h” )

Philosophy


哲學

A program is like
a cooking recipe

recipe

Ingredients

Computational explanation of
information processing in the mind


Thinking that P = activating a set of
symbols in the brain which mean P.

boring!

Is
-
in
-
love

Peter

Is
-
happy

Is
-
in
-
love

Is
-
happy

Symbols in the mind =

mental / neural representation

Topographical
representation of
visual stimulus in
visual area V1

Representations explain lots of things


Example: Syntactic Disambiguation



We shall discuss violence on TV.



Two interpretations :


VP

V

NP

NP

PP

N

discuss

violence

on

TV

P

VP

V

NP

N

discuss

violence

NP

PP

on

TV

P

Two methodological consequences of
the computer model


Computer models

can be built to test
theories of mental processes.


There are
different levels of analysis

for
a complex information processing system.

Three Levels of Description

(David Marr)


A complete understanding of a computational
system has to involve three (kinds of) levels :


Computational theory


What is computed and why.


What the system is capable of doing.


Representation and algorithm

(software)


What program is used.


What are the symbols and how are they processed.


Hardware


Where in the brain?


What kind of neurons and how are they connected?

Example


Task
: Multiplication.

Input numbers x and y.
Output x times y.


Algorithm
:

Given inputs x and y,

look up number z on

row x and column y.

Output z.


Implementation
:

human being and paper.

Alternative algorithm


How to calculate x times y:


If x =1, then answer is y.


If x>1, add y to itself (x
-
1) number of times.

The result is the answer.


Example: 3x5 = 5+5+5 = 15


Implementation:

Two points


The same task can be performed with
different algorithms.


Two different systems can do the same task in
very different ways.


The same algorithm can be implemented
with different hardware.

How to study cognitive science


A computational theory of X should
explain X at three levels.


What is computed? Visual motion


How? Correlate changes in luminance at
different places.


Hardware? Comparator circuits

http://www.psypress.co.uk/mather/resources/swf/Demo11_1.swf


Demo

http://www.psypress.co.uk/mather/resources/swf/Demo11_1.swf

Application: linguistic understanding


Task


Identify syntax and meaning corresponding to speech sounds.


Algorithm


What kind of computation and

mental representations?


Implementation


Which part of the brain?

VP

V

NP

NP

PP

N

discuss

violence

on

TV

P

INTERDISCIPLINARY approach


Division of labour


Psychology


cognitive psychology,
developmental psychology



Linguistics


syntax, semantics, phonology



Neuroscience


brain structures, localization



Computer science


AI, computer models



Philosophy


theoretical foundations


How to think about cognitive science

Language

Vision

Reasoning

Other
areas

Task

Algorithm

Hardware

If you get lost


Which mental process?


Language, reasoning, emotions, …


Which level?


Task, algorithm, neural implementation

Summary


Cognitive science is an inter
-
disciplinary
science of mind and behavior.


The computational approach : using
computations and representations to
explain mental processes.


Three levels of descriptions.


Coming up next: language as an example.