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CONSCIOUSNESS

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CONSCIOUSNESS Powered By Docstoc
					        LECTURE 6

COGNITIVE THEORIES OF
   CONSCIOUSNESS

          David Pearson
 Room T10, William Guild Building
  Email: d.g.pearson@abdn.ac.uk
           Cognitive Theories
What function does consciousness perform?

• Baar‟s Global Workspace Theory
• Dennett‟s Multiple Drafts Theory
• Shanon‟s Theory

• All three models share the assumption that human
  consciousness is not unitary in nature.
     Global Workspace Theory
•   Bernard Baars (1988; Baars et al., 1998) argues
    that the function of consciousness is to broadcast
    information to separate functional modules
    through-out the brain.
•   His „global workspace‟ is a central processor
    that contains the contents of consciousness.
•   The Workspace functions as a cognitive
    “blackboard”.
    Consciousness as a „Theatre‟
•   Baar‟s theory addresses the problem of
    access consciousness.
•   Consciousness is enabled by working
    memory, which provides a means to
    control what information can become
    conscious.
•   To explain his theory Baar uses the
    analogy of consciousness as a ‘theatre’.
•   Working memory provides the „stage‟ of
    consciousness.
•   We only become conscious of information
    held in working memory if it is selected
    by the central executive.
•   Central idea of Baar‟s theory is that once a
    representation becomes conscious it
    becomes available to other cognitive
    processes.
Criticism
• Baar‟s theory does not address the
   problem of phenomenal consciousness
   (i.e., Chalmer‟s „hard‟ problem).
        Multiple Drafts Theory
•   Daniel Dennett argues in his book
    Consciousness Explained (1991) that
    consciousness is not an all-or-nothing
    phenomena that occurs the same way every
    time.
•   Dennett rejects the idea of consciousness as a
    „theatre‟.
•   Consciousness does not occur in a single area; it
    is an abstraction.
•   The foundation of Dennett‟s theory is that the
    brain cannot process all incoming sensory
    information simultaneously.
•   The fact that we experience consciousness as
    being „on-line‟ is therefore an illusion.
•   Consciousness results from the activation of
    revised collections of sensory information called
    drafts.
•   Conscious experience is an updating, constantly
    revising process that takes into account sensory
    information arriving at different times and in
    different forms.
•   Dennett uses the analogy of an author constantly
    redrafting and revising a manuscript.
• Multiple drafts of sensory information are
    assembled at particular points in time to form
    the basis of conscious experience.
“Information entering the nervous system is under
    continuous „editorial revision‟…the Multiple
    Drafts model avoids the mistake of supposing
    that there must be a single narrative (the „final‟
    or „publishable‟ draft, you might say) that is
    canonical…”
                          Dennett, 1991.
Criticism
• Although Dennett rejects the concept of a
   single „theatre‟ of consciousness, it could
   be argued that his multiple drafts simply
   represent a larger collection of smaller
   such„theatres‟.
    Shanon‟s Consciousness Theory
•    Benny Shanon (1990; 1998) argues that
     consciousness comprises three distinct
     components.
•    Shanon‟s theory focuses on the phenomenology
     of human consciousness.
•    Argues that features that are specific to
     phenomenal experience are of distinct functional
     advantage.
•    Attempts to address issue of phenomenal
     consciousness.
(1) Sensed Being
• Ability to distinguish between animate
    and living and inanimate and dead.
• Sensed Being is a prerequisite of
    consciousness.
2) Mental Awareness
• Self-awareness of the contents of
    consciousness.
• This forms the core of conscious
    experience.
(3) Reflection
• Awareness of mental computations (or
    ‘mentations’) that can be the subject of
    future computations.
• Reflection is derived from conscious
    experience.
Meta-observation – reflection on the content
    of mental states
Monitoring or Control – control process that
    guides or governs thinking by checking
    and evaluating thoughts.
Criticisms
• Very difficult to empirically test Shanon‟s
   theory.
• Different components are vaguely defined
   – theory offers a description of
   consciousness rather than an explanation.
        Important Issues in
       Consciousness Studies
•   Can computers ever duplicate human
    consciousness?
•   Is consciousness really necessary in
    cognition?
     Does the brain work like a
            computer?
•   Over the last 40 years cognitive psychology has
    used microcomputers as an analogy for the
    human brain.
• General-purpose computers have three main
    features:
(1) Input and output devices that allow the user to
    communicate with the computer.
(2) A memory system that permits the storage of
    information.
(3) A central processor that controls the major
    functions of the computer.
•   In principle a computer can be
    programmed to duplicate the principle
    cognitive functions of perception,
    memory, and problem-solving.
•   Such computer simulations include visual
    pattern recognition, speech
    comprehension, reading, movement
    control, mental imagery, and memory.
•   The construction of computer programs
    that simulate human mental functions is
    called artificial intelligence.
Artificial Intelligence
•   Computer simulations require formal
    modelling of cognitive functions.
•   Establishing what steps are necessary for a
    computer to simulate a cognitive ability
    may give insight into the kinds of process
    the brain must perform.
•   Critics argue that computers may perform
    tasks in an entirely different way to the
    human brain.
•   Computer processing maps poorly onto
    human performance of similar tasks.
•   Majority of computers rely on serial
    processing.
•   In contrast the brain appears to utilise
    parallel processing.
•   Strong A.I. position states that a computer
    which exactly duplicates the functions of
    the brain would by definition become
    conscious.
•   Critics argue that true consciousness can
    never be achieved by an artificial non-
    organic system.
       Is Consciousness Really
             Necessary?
•   Being able to monitor and control our behaviour
    are consequences of information being shared
    across cognitive modules.
•   These are functions of access consciousness.
•   How important is phenomenal consciousness
    for cognitive functioning?
•   Philosophers use the concept of zombies.
Cognitive “Zombies”
•   „Zombies‟ are hypothetical beings that possess
    exactly the same cognitive processes as we do,
    but without conscious experience.
•   Conscious experience does not appear to be an
    inevitable consequence of cognitive and neural
    processing.
•   The majority of cognitive models do not feature
    a functional role for phenomenal consciousness.
•   Some argue that phenomenal consciousness is
    an epiphenomenon of neural and cognitive
    processing (i.e., a by-product that plays no
    functional role in the system).
                 Summary
•   Cognitive models of consciousness share the
    assumption that it is non-unitary in nature.
•   Artificial Intelligence creates computer
    programs that simulate human mental functions.
•   Access consciousness is essential for normal
    cognition.
•   Major issue in consciousness studies is what
    function phenomenal consciousness may play
    during human cognition.
             General Points
•   Make sure that you read the consciousness
    chapter in Martin. Also read the „Drugs
    and Behaviour‟ section in Chapter 4.
•   Also consider looking at alternative
    textbooks like Bernstein or Gleitman.
•   Questions on this section of the course
    will feature material from all six lectures.

				
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