Joe Lau's wiki: Courses/2008a COG N1001intro

What is cognitive science? An introduction

Readings

• [Required] http://plato.stanford.edu/entries/cognitive-science/
• [Required] A brief intro from Berkeley's cognitive science programme at http://ls.berkeley.edu/ugis/cogsci/major/about.php
• Thagard, Paul (1996). Mind : Introduction to Cognitive Science Cambridge, Mass: MIT Press. [accessible from netlibrary.com]
• Howard Gardner (1985). The Mind's New Science: A History of the Cognitive Revolution

What is cognitive science?

Definition : cogsci = the science of mind and behavior

1. Cognitive science is a very wide subject.
   • All sorts of internal mental phenomena: Thinking, emotions, reasoning, language, feelings, etc.
   • All sorts of behavior: bodily movements, facial expressions, speech, etc.
   • Both normal and abnormal cases: prosopagnosia, autism, Cotard syndrome, Anton syndrome, alien hand, etc.
   • Note: focus upon an individual's mental capacities.
2. Cognitive science is a science.
   • Theories must be testable - use experiments to check the predictions made by a theory.
   • If the predictions are confirmed, we are more confident of the theory.
   • If the predictions are wrong, we reject the theory, modify it, or check our experiments again.
   • Some examples of experiments: brain scans, psychophysics experiments, studies of cognitive deficits, reaction time, computer simulation.
3. Cognitive science places special emphasis on the use and acquisition of knowledge and information.
   • Information is the key to understand the mind.

Cognitive science is very useful and important

1. The mind is the final frontier of science.
2. Whether the mind can be scientifically explained has great metaphysical and religious significance.
3. Cognitive science has lots and lots of applications
   • Education, language teaching
   • AI and robotics Main/BrainReading
   • Mental health, addiction, psychiatry
   • Marketing
   • Management

History of cognitive science

Cognitive science is relatively young science, but the study of the mind has a very long history.

Long history: the mind has always been an area of investigation

• Philosophers and scientists were interested in understanding the mind long before cognitive science.
  • Philosophers - Plato, Aristotle, Descartes, Hume, Kant, etc.

• Hippocrates (400BC) - "Father 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.@

• The beginning of modern psychology
  • Wilhelm Wundt (1832-1920) - First psychology laboratory
  • William James (1842-1910) - The Principles of Psychology

Young science

Cognitive science came about in the 1960s as a result of different disciplines coming together. Very briefly, it was the result of three main developments:

• The reaction against behaviorism in psychology, linguistics and philosophy;
• The emergence of AI and computational theory in computer science; and
• New discoveries about brain functions in neurophysiology.

@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.@

The unifying theme was that to explain the mind we need to understand how information is processed in the brain.

A brief history of cognitive science

Rejection of behaviorism in psychology

• Famous behaviorists: Pavlov, Skinner, Thorndike, Watson, etc.
• What is behaviorism?
  • Scientific psychology should focus only on observable behavior.
  • Behavior to be explained in terms of conditioning.
  
• Response: Psychological explanations must take into account internal mental states that are not directly observable.
  • George Miller (1956) “The Magical Number Seven, Plus or Minus Two”
  • Chomsky (1957) Syntactic Structures
  • Chomsky (1959) A Review of B. F. Skinner's Verbal Behavior

The start of modern computing and AI

• Mathematical definition of computation: Turing, Church, Post
• Electronic computers - The beginning of AI
• Famous names: John McCarthy, Marvin Minsky, Allen Newell, Herbert Simon
• The analogy of the mind as a computer turns out to be very fruitful.
  • Focus questions on information processing
  • Intelligence as the product of dumb computations
  • Efforts in AI: The famous Eliza computer program.

Developments in neurophysiology

• Brain functions and information processing in neurons
• Famous names: Penfield, Hubel and Wiesel, Sperry, Melzack and Wall
• Localization of brain function, neural correlates, imaging of mental/brain processes

Topographical representation of visual stimulus in area V1

Methodology of cognitive science

• Cognitive science is the science of mind and behavior. What is special about this discipline? How does it compare to neurophysiology / psychology?
• Summary: All mental processes are to be explained by parallel neural computations in the brain.

1. The BRAIN explains ALL mental processes

• Mental phenomena are explained in terms of physical processes in the brain. Most cognitive scientists are PHYSICALISTS (or MATERIALISTS) - everything in the world is made up of physical substance.
• PHYSICALISTS would deny SUBSTANCE DUALISM - the view that the mind is a soul, some kind of non-extended and non-physical object. Substance dualism is of course a part of most religious doctrines.
• We have no a priori reason to think that substance dualism must be wrong. Only observations and experiments can help us decide which approach is more likely to be true. The fact that we WANT theory X to be true / we HOPE that theory X is true does not make theory X true.
• So far it seems that the physicalist approach has been more successful in improving our understanding of the mind. How would a dualist explain:
  • Damage to the (frontal lobe of the) brain can change our personality
  • Damage to the back (e.g. the primary visual cortex) of the brain can cause blindness
  • Alcohol can affect our balance and consciousness
  • Some thoughts correspond to specific patterns of activities in the brain:

@Example: Haynes, J-D. and Sakai, K. and Rees, G. and Gilbert, S. and Frith, C. and Passingham, R.E. (2006) Reading hidden intentions in the human brain. Current Biology, 17 (4). pp. 323-328. doi:10.1016/j.cub.2006.11.072

Here we study subjects who freely decided which of two tasks to perform and covertly held onto an intention during a variable delay. Only after this delay did they perform the chosen task and indicate which task they had prepared. We demonstrate that during the delay, it is possible to decode from activity in medial and lateral regions of prefrontal cortex which of two tasks the subjects were covertly intending to perform.@

2. COMPUTATION is the key to the explanations

The distinctive feature of practically all mental processes is that they involve complex information processing.

• 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

But complex information processing is best explained by computations and representations.

• What is 23 x 54

• A program is a set of rules for manipulating symbols, e.g. FOR F=1 TO 10; PRINT F; NEXT F

Conclusion: We have reasons to believe that mental processes should be explained by computations in the brain. There are mental representations that encode information, and there are mental processes that operate on such representations.

Examples:

The sentence we shall discuss violence on TV is ambiguous.

3. PARALLEL NEURAL computation

The mind is extremely complicated

• Around 100 billion inter-connected neurons

An incomplete connection diagram of the visual areas:

motion detection system: http://www.physpharm.fmd.uwo.ca/undergrad/sensesweb/L4Motion/L4Motion.swf

4. Cogsci is interdisciplinary

Vertical and horizontal division of labour is needed to understand the mind.

• Horizontal division of labour: Mental phenomena involves language, perception, reasoning, emotions, etc. Different scientists focus on different areas.
• Vertical division of labour: Each mental phenomena can be investigated at various levels - the task level, the level of algorithm, and the level of neural mechanism.

Some of the disciplines of cogsci:

• Psychology - cognitive psychology, developmental psychology
• Linguistics - syntax, semantics, phonology
• Neuroscience - brain structures, localization
• Computer science - AI, computer models
• Philosophy - theoretical foundations

5. The mind is modular

• The brain is a complex system with different functional parts, e.g. visual areas, language, reasoning, ...
  • Broca's area is related to language production.
  • Area MT is related to perception of visual motion.
  • FFA is related to face perception.
  • The amygdala is related to emotions.
• Cognitive science is more like reverse engineering - understanding a complex system by identifying the functions of different parts and see how they interact. piano

6. Most mental processes are unconscious

We are not consciously aware of much of our mental processes.

• We have lots of different beliefs at any given time, but we are not aware of all of them at the same time.
• We are not aware of how we retrieve information from memory, how we recognize faces, ...
• As a result most people underestimate the power of scientific explanations of the mind.

Demo

• Biological motion perception: http://www.psypress.com/mather/resources/swf/Demo11_7.swf
• Attribution of social causality: doi:10.1177/1362361300004002004