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Theoretical Issues in Psychology

Theoretical Issues in Psychology. Philosophy of Science and Philosophy of Mind for Psychologists. Chapter 8 Modern approaches to mind (2). Neural networks and connectionism ‘Classical’ versus connectionist architecture The third contender: dynamicism

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Theoretical Issues in Psychology

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  1. Theoretical Issues in Psychology Philosophy of Science and Philosophy of Mind for Psychologists B&LdJ

  2. Chapter 8 Modern approaches to mind (2) • Neural networks and connectionism • ‘Classical’ versus connectionist architecture • The third contender: dynamicism • Is there need for ‘mental representations’? • Naturalism, reductionism and folk psychology B&LdJ

  3. Neurophilosophy (the Churchlands) • Contrary to Fodor’s ideas: • For answers to philosophical-psychological questions turn to the neurosciences (empirical knowledge - naturalism). • No autonomy for psychology. • Brain-based view of mind: ‘mind is brain’ (but no mind-brain identity). • Eliminate folk-psychological concepts. • Against sentential (propositional) LOT-view of knowledge. • No solipsism, but evolutionary adaptation. B&LdJ

  4. Model of a neural network • Set of nodes and connections between them. • Activation spreads through the network. • Giving weights to the nodes. • Three layers: input, output, midden layer of hidden nodes. • Network learns by adjustments of weights. • According to some learning rule (‘Hebb rule’). • Does the training by itself, is tuned to the environment (is • not pre-programmed). • Maintains fault tolerance, graceful degradation (functional persistence), and satisfies soft constraints (all unlike programs). • Knowledge/representations is/are distributed over many connections. • Network is model of human mind: ‘connectionism’. B&LdJ

  5. Working of a (quasi-neural) network (here, a network of a submarine, learning sonar signals) B&LdJ

  6. Activation space and prototypes • Learning to recognize is forming a prototype, a hotspot in a vector or activation space. • A concept is a prototype (not a symbol string). B&LdJ

  7. Connectionism (Quasi-)neural networks: ‘neural’ patterns of activation (versus symbols and inborn rules); online selforganisation (versus offline programs); support cognitive tasks. Basic cognitive processes (formation of representations) are patterns of activation (not manipulation of symbols). Cognition is basically pattern recognition. Neurophysiology, c.q. neural networks, explains cognition: ‘cognitive neuroscience’, cognitive theories which are neurological plausible and naturalized: no functionalism; no autonomy for psychology. B&LdJ

  8. Representational capacity of human brain • Human brain has: 100 billion neurons = 100.000.000.000 (1010). • Every neuron has: synaptic connections with 10.000 (104) other neurons. • In a human brain:1014 synaptic connections. • Weight of each connectioncan have a value of 1 out of 10. • Thus human brain can contain: • 101014 = 10100.000.000.000.000 • cognitive configurations • (cfr. total elementary particles in universe estimated 1087). B&LdJ

  9. Symbolic versus connectionistic systems Fodor: thinking is characterized by productivity, systematicity, i.e. a continuous recombination of discrete symbols: compositionality, like building sentences with words: requires formal structure (networks lack structure and are not strong enough to simulate cognition; leaves you with nothing more than a plain associationpsychology); so, LOT is ‘the only game in town’: thinking occurs in a formal language; the only explanation of structure. Connectionists (a.o. Smolensky): thinking is network activation, compositionality is a by-product of networks: ‘functional compositionality’: doesn’t need a symbolic architecture; productivity of language is not the only possible productivity (Churchland). B&LdJ

  10. Third Contender: Dynamism: ‘mobots’ and dynamic systems • Dynamic coupling of organism and environment. • Activity in environment (no inner representational domain). • Online interaction (no innate structure and programs). • Evolution and time (no static representations). • Adaptation. • Dynamic system (no representational structure: LOT or patterns of activation). • Cognition is like playing tennis, rather than chess. B&LdJ

  11. Dynamism: mobots • Mobots : internalrepresentations and computations redundant. • Rodney Brooks: robot with response systems, direct interaction with environment, without central representations. B&LdJ

  12. Dynamism: Watt governor Cognition is on-line real-time interaction with the environment – Watt governor, continuous following and control of behavior and environment; reciprocal causality. B&LdJ

  13. Mental representations redundant? • The absent and the abstract: • there are ‘representation-hungry’ situations. • that require higher cognitive functions like abstract thinking, imagination and reflection. • Direct coupling mainly in sensori-motor functions. • External symbols for higher cognitive tasks (planning, abstraction). • ‘Active externalism’ (extended mind, Ch 9.4): for some cognitive tasks we use external instruments, e.g., paper and pencil, graphical devices; books, internet. • ‘Leaky cognition’: brain and environment cannot be separated. • Andy Clark (1997, 2003) B&LdJ

  14. Naturalism and neurophilosophy Churchland • Naturalism: representation is biological phenomenon, product of evolution. • Cognition is pattern recognition, not symbol manipulation. • Language appears late in evolution, therefore no LOT. • Functionalism is a conservative ‘cheap# explanation. • Folk psychology (beliefs and desires) stagnating program, isolated from scientific progress. • Folk psychology eliminated and replaced by neuro-speak. B&LdJ

  15. Churchland: Naturalism and neurophilosophy • Naturalistic (neuroscientific) explanations of: • knowledge as coded in connection weights; • representation and intentionality as processes in the brain; • sense of self; • morality as cognitive skill; role of oxytocine in building trust and love. B&LdJ

  16. Eliminativism and folk psychology • Folk psychology (‘belief-desire’) is a kind of theory, explains behavior (Fodor + Churchland). • Fodor: in principle correct theory: • beliefs and desires exist really as symbol structures in LOT; • are causes of behavior; • folk ps. vindicated by CTM; • intentional laws, generalisations, and predictions indispensable: folk psychology is successful predictor; • intentional realism. B&LdJ

  17. Eliminativism and folk psychology • Churchland: folk psychology obsolete theory: • stagnating program (Lakatos); • no progress, no connections with current development in science; • replace by neuroscience; • eliminativism. • Clark, Dennett: folk psychology is not ascientific theory, • beliefs and desires only descriptive (‘intentional stance’), not internal causes (‘design stance’), not literally true; • different explanatory aims; different level from neuroscientific explanation; • instrumentalism. B&LdJ

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