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COGN1001 Introduction to Cognitive Science

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.

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COGN1001 Introduction to Cognitive Science

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  1. COGN1001Introduction to Cognitive Science Sept 2006 :: Lecture #1 :: Joe Lau :: Philosophy HKU

  2. Please write this downhttp://philosophy.hku.hk/courses/200607/cogn1001

  3. Topics • About this course • What is cognitive science? • The computer model of the mind

  4. About this course

  5. 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.

  6. What iscognitive 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.

  7. How is it differentfrom psychology? What is cognitive science? Cognitive science is the science of mind and behavior.

  8. “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.

  9. 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.

  10. 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.

  11. Explaining information processing • What is the best explanation of why a system is capable of complex information processing? • Answer: The system is a computer.

  12. 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

  13. VIP #1Cognitive science is about how the mind processes information.

  14. 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

  15. Psychology Cognitive science Social psychology Educational psychology

  16. More on the computer model of the mind

  17. Quiz: What is a computer? (a) A person (b) A machine

  18. 17x11=? 170 17 187 What is computation? • Rule-based manipulation of symbols. S = str_replace( “cat” , ”c” , ”h” ) Philosophy  哲學

  19. A program is like a cooking recipe Ingredients recipe

  20. Is-in-love Is-happy 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

  21. Symbols in the mind =mental / neural representation Topographical representation of visual stimulus in visual area V1

  22. VP VP NP V NP PP V discuss N PP discuss N P NP violence P NP violence on TV on TV Representations explain lots of things • Example: Syntactic Disambiguation • “We shall discuss violence on TV.” • Two interpretations :

  23. 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.

  24. 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?

  25. 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.

  26. 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:

  27. 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.

  28. 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 circuitshttp://www.psypress.co.uk/mather/resources/swf/Demo11_1.swf

  29. Demohttp://www.psypress.co.uk/mather/resources/swf/Demo11_1.swfDemohttp://www.psypress.co.uk/mather/resources/swf/Demo11_1.swf

  30. VP NP PP V discuss N P NP violence on TV 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?

  31. 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 …

  32. How to think about cognitive science

  33. If you get lost • Which mental process? • Language, reasoning, emotions, … • Which level? • Task, algorithm, neural implementation

  34. 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.

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