Joe Lau

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.

  • 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

Other features of cognitive science

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