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Psychology 485 September 28, 2010

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Introduction & History Three major questions: What is learned? Why learn through classical conditioning? How does learning happen?

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Often contrasted to more cognitive approaches Watson & Little Albert A premise: Study of simple learning processes will scale up to complex cognition

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Pavlovian (Classical) conditioning Physiologist Digestion Dogs Conditional redirection of reflexes Conditional reflexes

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TIME Conditional Stimulus on off Unconditional Stimulus on off Unconditional Response (after enough pairings) Conditional Response

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The originally neutral stimulus, through repeated pairings with the unconditioned one, acquires the response originally given to the unconditioned stimulus Intro Psych textbook from 1987 What is wrong with this definition?

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Taste aversion Idea of contiguity Temporal similarity between presentation of CS and US i.e. CS and US are presented at the same time Contiguity is neither sufficient nor necessary

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GroupInitial Training Second Training TestOutcome Control Group NothingTone + Light Food Light ?Moderate response to Light Blocking Group Tone FoodTone + Light Food Light ?Little response to Light During second training, tone & food are contiguous Contiguity not sufficient

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Which CS would condition more easily? Contiguity is the same CS2: US is contingent (dependent) on CS Contingency, not contiguity CS1 CS2

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No contiguity between CS and US CS signals absence of US Conditioned inhibitor Contiguity is not necessary for conditioning CS1

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The originally neutral stimulus, through repeated pairings with the unconditioned one, acquires the response originally given to the unconditioned stimulus Intro Psych textbook from 1987

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CERs (Conditioned Emotional Response) Pair tone with shock When rat is shocked, it jumps and increases activity What tone is presented, rat freezes Drug tolerance CSs for drug use cause body to prepare for drug Body prepares in opposite direction of drug

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Context Hierarchical structure Second-order conditioning Occasion-setting Expectancies

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What type of association is formed? Stimulus-Stimulus Stimulus-Response US CS Response

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So, how do you get rid of a response that is hard wired to a stimulus? How can you get rid of a reflex? Habituation

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Less suppression in Habituation group (In other words, more responding) Therefore, the connection MUST be S SGroup Phase 1 Phase 2 TestHabituation L N (startle) Noise (habituate) Light Control L N (startle) NothingLight

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NoiseStartle Light

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Expectancies CS helps you predict occurrence of US Makes animal more able to react to US Biological relevance Not all CSs are created equal e.g. bright-noisy water vs novel-tasting water Hard to condition visual/auditory stimuli to nausea

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Blue Gourami Territory is defended more aggressively when competitor is signaled Winners become winners Losers stay losers

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Japanese Quail Signalling opportunity for reproduction Increases effectiveness of copulation (quicker and more ejaculate) Increases likelihood of fertilization

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Ant Lions Signal food presentation for larvae Build better pits Extract food more effectively Moult more quickly (quicker to reproduce)

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Baldwin effect If there is a reliable predictor of some important event across generations: Learning faster is better Learning becomes instinct? e.g. New predator in environment Some behaviour makes it difficult for predator to kill prey Learning behaviour provides survival advantage Selection: ability to learn improves Eventually behaviour becomes instinct

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Computational model of conditioning Widely cited and used Most important paper in animal learning? Learning as a violation of expectations

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Error Calculation

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On every trial: 1. Look around and examine all your stimuli 2. Use them to predict what will happen (V ) 3. Get a reward/US. How good/big was it? ( ) 4. How wrong was your prediction? ( - V ) 5. Take a portion of that error ( and ) 6. Change your prediction for next time ( V)

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And Voila! You have a learning algorithm. V = ( - V ) = the maximum conditioning possible = saliency of the CS (between 0 and 1) = saliency of the US (between 0 and 1) V X = associative (predictive) strength of a given stimulus V X = change in the associative strength of a given stimulus V = total associative strength of all stimuli

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Equation describes a change in expectancies Change in expectancy is based on: Features of the CS and US Total possible learning, minus what youve already learned Based on expectation of US

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Does not account for many Classical Conditioning findings: Spontaneous recovery Savings CS pre-exposure (latent inhibition) Higher-order conditioning Trial-by-trial based account Does not account for timing

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CS processing theories suggest properties of CS affect learning Attentional theories: its adaptive to pay attention to CSs that may signal important events Also adaptive to not pay attention to CSs that are not likely to signal important events Pearce-Hall model Attention to CS changes across trials can change from trial to trial