Introduction to Cognitive Science

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Introduction to Cognitive Science

• Sept 2005 Lecture 1 Joe Lau Philosophy
  HKU

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Topics

• About this course
• What is cognitive science?
• Methodology
• The computer model of the mind

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About this course
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About this course

• Course coordinator
• Joe Lau
• Other teachers
• Course tutors
• Antonio Cheung and Elaine Lau
• Course web site
• http//philosophy.hku.hk/courses/cogn1001
• Assessment
• 60 exam -- 2 hours.
• 25 problem sets -- 5 problem sets one for each
  topic.
• 10 tutorial participation.
• 5 tutorial attendance.

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What is cognitive science?
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What is cognitive science?

• Answer Cognitive science is the science of mind
  and behavior.

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Feature 1

• Cognitive science studies MIND AND BEHAVIOR
• Mental states and processes inside the brain
• Emotions, knowledge of language, reasoning
• The behavior caused by these processes
• Facial expressions, speech
• The normal mind
• The abnormal mind
• Autism, Cotard delusion

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Feature 2

• Cognitive science is a SCIENCE.
• Theories and hypotheses have to be tested.
• How? Check whether they can explain the data from
  experiments and observations.

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Why study cognitive science?
Man is the Measure of all Things. Protagoras
of Abdera ( c. 480-410 B.C.)

• Intellectual value
• Practical value
• Education
• AI and technology
• Medical application
• Educational value
• Entertainment value!

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Methodology of cognitive science
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Methodology

• Some distinctive features about research methods
  and explanations in cogsci.
• Brain-based explanations
• Functional explanations
• Interdisciplinary approach
• The computational model of the mind

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400 BC - Hippocrates

• Founder of Western medicine
• Men ought to know that from the brain, and from
  the brain only, arise our pleasures, joys,
  laughter and jests, as well as our sorrows,
  pains, grievances, and tears. Through
  it...we...think, see, hear, and distinguish the
  ugly from the beautiful, the bad from the good,
  the pleasant from the unpleasant.

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Brain-based explanations

• The mind is explained in terms of physical
  processes in the brain. (pace Aristotle)
• What about Dualism?
• Dualism - The mind is a soul.
• Not to be decided a priori. Need experiments.
• BBE is the default hypothesis because it has been
  more successful and has better predictive power.

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However, the brain is a very, very, very complex
system. (100 billion neurons vs. 6 billion people)
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Some of the connections between the different
visual systems.
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How to deal with this complex system?

• 1. Functional approach
• Understand the functions of different systems of
  the brain and see how they interact.
• Visual areas, language, emotions
• Cognitive science is like reverse engineering.
• 2. Inter-disciplinary approach

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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

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The computer model of the mind

• The mind is like a computer.
• A distinctive feature of cognitive science.

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What is the computer model?

• The mind is an information processing system.
• Information processing is best explained by
  computations and symbols.
• Information processing in the computer programs
  operating on symbols.
• Information processing in the brain neural
  computations involving mental representations.

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A typical computer

• Inside a computer, we have
• Symbolse.g. HTML color codessymbols are
  objects to which meaning can be assigned.
• Programse.g. Str_replace( I have a cat , c ,
  h )programs are procedures for manipulating
  symbols.

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Mental representations

• Mental representations are symbols in the brain
  that have meaning or encode information.
• Thinking P Activating a mental representation
  that means P.

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Thinking as neural computation
Is-in-love
Peter
Is-happy
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Why should we accept the computational model of
the mind?
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Some reasons

• Information processing does seem to be a
  distinctive feature of the mind.
• Mental representations are useful in explaining
  lots of mental phenomena.
• We can observe mental representations.

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Information processing in the mind

• 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

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They help us explain lots of things

• Example Syntactic Disambiguation
• We shall discuss violence on TV.
• Two interpretations

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A real representation
Topographical representation of visual stimulus
in area V1
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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.

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Three Levels of Description (David Marr)

• A complete understanding of a computational
  system has to involve three (kinds of) levels
• Task what the system is capable of doing
  (capacities)
• Algorithm (software) which computational
  procedures are used
• Implementation (hardware) how the computations
  are implemented

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Example
1 2 3 4 5
2 4 6 8 10
3 6 9 12 15
4 8 12 16 20
5 10 15 20 25

• Task Multiplication
• Algorithm input numbers x and y. Output number
  in row x and column y.
• Implementation human being and paper.

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Different algorithmsSame task

• Task calculate X2-1
• Algorithm 1 X2-1 (X1)(X-1)
• 52-1 (51)(5-1) 64 24
• Algorithm 2 X2-1 XX-1
• 52-1 (55)-125-124

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Same taskDifferent hardware implementations
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2 4 6 8 10
3 6 9 12 15
4 8 12 16 20
5 10 15 20 25
Exercise Can you give an example where the same
algorithm is implemented in different hardware?
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Application linguistic understanding

• Task
• Identify grammatical structure and meaning of
  speech sounds.
• Algorithm
• What kind of computation and mental
  representations?
• Implementation
• Which part of the brain?

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How to think about cognitive science
Language Vision Reasoning Other areas
Task
Algorithm
Hardware
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If you get lost

• Which mental process?
• Language, reasoning, emotions,
• Which level?
• Task, algorithm, neural implementation

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Summary

• Cognitive science as an inter-disciplinary
  science of mind and behavior.
• The computational approach using computations
  and representations to explain mental processes.
• Three levels of descriptions.

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Finally, to end
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Scope of the computer model?

• Computations are NECESSARY for understanding the
  mind because the mind processes information.
• Are computations SUFFICIENT for understanding
  everything about the mind?