COGS 101B Slides Outline History Descartes
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COGS 101B Slides • Web Page • PDF version of Powerpoint slides available – http://www.cogsci.ucsd.edu/~coulson/101b/ on the course website • Instructor http://www.cogsci.ucsd.edu/~coulson/101b/ – Dr. Coulson – Email: coulson “at” cogsci.ucsd.edu – CSB 161 – Thursday: 12-2pm •TAs – Alan Robinson – Nate Harrison – Zack Weinberg Outline History •History • Philosophical Origins • Methods • Structuralism • Paradigms • Functionalism • Gestalt Psychology • Genetic Epistemology • Behaviorism • Cognitive Revolution Descartes • Epistemology • Radical Skepticism • Evil Demon • “Cogito ergo sum.” • Leap of Faith 1 Premises & Problems Rationalism vs. Empiricism Kant Locke, Hume • Knowledge begins • All knowledge originates Physical Neural Mental w/experience but is in experience Energy Activity Experience constructed by mind • Mind is a blank slate • Experience mediated by mental categories or qualia – “raw feels”, raises problem of how to relate physical schemata facts to mental facts Structuralism • Philosophical Motivation – Belief in reductionism – Consciousness can be broken down into basic elements • Goal – Discover basic structures of mental life • Methodology – Introspection Wundt Titchener • Founded first • Took introspection to new experimental psychology level laboratory • “Tell me your sensations • Not just sensations but of this rock” thoughts • BUT: Also did lots of • Tell me your reactions to psychophysics “green things” • Most introspection was people saying “yes” or • Unfortunately, “no” to targeted questions inconsistencies about their perceptions abounded 2 Pros & Cons of Functionalism Introspectionism • Psychology of mental operations • Creative Synthesis • (Not Mechanistic) – Not mental elements • Irrelevance: cognitive • Evolutionary Motivation • Chief Virtue processes not always – Consciousness must have a function – Acknowledged available to • Consciousness still central volitional character of consciousness – mediates between needs of organism and demands of human behavior – People confabulate environment – Not mechanistic • Subjective • Asks – Not public – What do people do? – Not replicable – How do they do it? – Often results in – Why do they do it? contradictory findings William James Gestalt Psychology • Dynamic, streaming • Like functionalists, anti- quality of consciousness reductionistic • Consciousness central to life and biological survival • The whole of conscious • Respect for individual experience is greater differences than the sum of its parts. – Different people arrive at the same conclusion via • Discovered many visual different paths illusions •Wrote Principles of • Characterized principles Psychology of perception Genetic Epistemology Behaviorism • Piaget • Empirically-based science of behavior • “Genetic” – Experimental analysis of stimulus-response (S-R) – Not just DNA, but genesis in the larger sense – Dominant in American psychology • “Epistemology” • Mental or cognitive phenomena are not good candidates • Tenets for scientifıc inquiry – Knowledge arises out of action and has a biological – not meaningful to study function – (almost) impossible notions for scientific investigation – Knowledge consists of cognitive structures • Carefully controlled lab studies of animal learning – Change via assimilation, accommodation – Capacity for abstraction develops over the lifespan 3 Watson • Attacked Introspectionism • Concerned only with external behavior • “…consciousness is neither a definite nor a usable concept.” • “dropped from his scientific vocabulary all subjective terms such as sensation, perception, image, desire, purpose, and even thinking ….” Paradigms Cognitive Revolution • What is a paradigm? • Paradigms vs. Hypotheses – Experimental paradigm: p • Paradigms organize research programs – Scientific Paradigm: P • Evaluated based on – popularity – internal consistency – consistency with facts Downfall of Behaviorism Garcia Effect • Differences between • Does learning proceed the same way in every animal species species? • Need to postulate • Are all stimuli & responses equally likely intervening variables to be associated w/one • Language behavior another? • Radiation vs. Shock on Taste Aversion vs. Tone Aversion • Rats drink sweetened water, hear tone – Some shocked – Some X-rayed (get sick) 4 Garcia & Koelling Cognitive Maps • Tolman’s research suggests need for intervening variables Shock X-Rays Saccharine Loud Saccharine Loud • S [int. var.] R Taste Tone Taste Tone • Path 1 shortest (no effect) aversion aversion (no effect) • A blocked, take 2 • B blocked, now what? • Flood!!! Chomsky’s Critique What constitutes reinforcement? • Behaviorism OK in lab, • “Your money or your but what about the real world? life!” • Painting is stimulus • What reinforces “your – It’s Dutch. life”? – It’s hideous. – It’s hanging too low. • If Skinner says, – I thought you liked abstract “reinforcement can be art. imagined,” he admits • Concept of stimulus to mental events. doesn’t explain much Unicorns Creative Use of Language • How do people refer • Most sentences are novel. to non-observable • When associated w/ a stimulus? phenomena? • “The ketchup bottle was being used as a weight • If stimulus must be to hold the money down, but when the ace of present for spades fell from his right sleeve, the bottle conditioning, it can’t became a lethal weapon.” explain most • Speakers can produce and comprehend an language use. infinite number of sentences!! 5 Rules Paradigm Shifts • Words + Rules = Infinity • Dissatisfaction with • A stimulus is tied to current approach particular event – Anomalies – Absurdities • A rule is general – Perceived Omissions • Rules explain novelty and • New approaches productivity in attractive because they – Language resolve absurdities – Thinking • Phenomena not – Understanding explained by old paradigm become focus of new Reemergence of Cognitive Psychology • Introspectionists – naive belief in power of self-observation • Behaviorists – naive belief in reducibility of intelligent behavior • Cognitive Psychologists (middle road) – Information Theory – Artificial Intelligence – Linguistics Information Processing v. Behaviorism Both IP Psychologists • Committed to theory • Fear not the mental building • Shifted emphasis • Believe in scientific from learning to observation – Perception • Laboratory – Memory experiments with – Thinking controlled conditions – Language 6 Information Theory The Computer Analogy Message Transmitter Receiver Channel InputEncoding CPU Encoding Output • Coding – rules for transforming messages, codes, etc. from one representation to another Storage • Channel Capacity – how many signals can the channel (disk) carry? • Serial vs. Parallel Processing – one vs. many messages The beauty Minds, Brains, and Computers of the computer analogy: • Computers provide a concrete way of Abstract Marr’s Levels of Explanation characterizing abstract mental operations. Concrete Computation New Solution to Mind/Body Problem Algorithm Architecture (Don’t) Dump the Program mind Implementation Postulate a level of explanation between mind and body Information Processing Model Sternberg Paradigm Sensory Physical Sensory Information Immediate Signal Processing RT to Probe registers behaviour • Give subjects a 700 653 small set of 618 600 575 Maintenance 540 500 500 numbers to 463 Rehearsal 400 425 remember: {3,9,6} 300 200 100 Intentional Short Term • Probe: 9? Reaction Time (ms) behaviour memory 0 012345678 Elaborative • Task: Respond as Set Size Rehearsal fast as possible Long Term memory Time= 387 + 38s 7 Ways Sternberg’s theory Sternberg’s Model exemplifies IP approach • Discusses IP without reference to brain processes • Symbolic operations (not subsymbolic, Yes 9 Perceive Make Generate not neural) Stimulus 9=3? 9=6? 9=9? Decision Response • Use of computer metaphor • Reaction time important for verification – Discrete stages – Flow-chart Paradigms Research Methods • Information Processing • Naturalistic Observation • Connectionism • Introspection • Cognitive Neuroscience • Behavioral Experiments • Evolutionary • EEG/MEG Experiments • Ecological • Neuroimaging Experiments • Single Cell Recording Cognitive Science • Still often employ computer • Parallel processing models metaphor popular • Characterize cognitive • Not exclusively symbolic processes in terms of simple processes, sub-symbolic processes can be important computational operations too • Still test theories with reaction • Also test theories with brain time studies imaging technologies (ERP, fMRI) • Increased importance of understanding relationship between mind and brain • Increased importance of social, cultural, and technological contributions 8.