Presentation on theme: "LECTURE 6 COGNITIVE THEORIES OF CONSCIOUSNESS"— Presentation transcript:
1LECTURE 6 COGNITIVE THEORIES OF CONSCIOUSNESS David PearsonRoom T10, William Guild Building
2Cognitive Theories What function does consciousness perform? Baar’s Global Workspace TheoryDennett’s Multiple Drafts TheoryShanon’s TheoryAll three models share the assumption that human consciousness is not unitary in nature.
3Global 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”.
4Consciousness 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’.
6Working 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.
7CriticismBaar’s theory does not address the problem of phenomenal consciousness (i.e., Chalmer’s ‘hard’ problem).
8Multiple 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.
9The 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.
10Dennett 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.
11CriticismAlthough 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’.
12Shanon’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.
13Sensed BeingAbility to distinguish between animate and living and inanimate and dead.Sensed Being is a prerequisite of consciousness.2) Mental AwarenessSelf-awareness of the contents of consciousness.This forms the core of conscious experience.
14(3) ReflectionAwareness 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 statesMonitoring or Control – control process that guides or governs thinking by checking and evaluating thoughts.
15CriticismsVery difficult to empirically test Shanon’s theory.Different components are vaguely defined – theory offers a description of consciousness rather than an explanation.
16Important Issues in Consciousness Studies Can computers ever duplicate human consciousness?Is consciousness really necessary in cognition?
17Does 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:Input and output devices that allow the user to communicate with the computer.A memory system that permits the storage of information.A central processor that controls the major functions of the computer.
18In 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.
20Computer 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.
23Majority 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.
24Is 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.
26‘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).
28SummaryCognitive 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.
29General PointsMake 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.