Transcript LT2Ch1
Introduction to Learning Chapter 1 A Definition of Learning Learning is: An experiential process Resulting in a relatively permanent change Not explained by temporary states, maturation, or innate response tendencies. Three Limits on the Definition The change that occurs during learning is a potential for behavior that depends on other conditions. Learning is not always a permanent change. What can be learned can be unlearned. Changes also occur for other reasons – maturation, motivation. Roots of Behavior Theory Functionalism – behavior promotes survival, study behavior to understand its adaptive function. Dewey – lower animals have reflexes, humans have a flexible mind James – people have instincts Brucke – internal biochemical forces motivate behavior in all species. Criticisms of Functionalism The variety of behavior across cultures is inconsistent with universal human instincts. Infants seem to have few innate instincts (only fear, rage, love?). Labeling everything an instinct doesn’t aid understanding much. Bernard cataloged 2000+ instincts Behaviorism A search for the laws governing learning. Emphasis on experience. Avoidance of mentalistic concepts. Based on Aristotle’s idea of the association of ideas. In order for two ideas to become associated, they must be paired together in time (temporally). British Associationists Locke – thinking consists of: Simple ideas – passive impressions received by the senses. Complex ideas – the combination (association) of simple ideas (a rose). Hume – associations are based on: Resemblance (similarity) Contiguity in time or place Cause and effect Thorndike’s Puzzle Box http://www.youtube.com/watch?v= BDujDOLre-8 Thorndike’s Laws Also called S-R learning. Law of effect – A chance act becomes a learned behavior when a connection is formed between a stimulus (S) and a response (R) that is rewarded. Law of exercise – the S-R connection is strengthened by use and weakened with disuse. Thorndike’s Laws (Cont.) Law of readiness – motivation is needed to develop an association or display changed behavior. Associative shifting – a learned behavior (response) can be shifted from one stimulus to another. Once a behavior is learned, the stimulus is gradually changed. Fish + “stand up”, then “stand up” alone. Pavlov’s Studies Pavlov’s Conditioned Reflex Conditioning -- a stimulus that initially produces no response can acquire the ability to produce one. Learning occurs through pairing in time and place of one stimulus with another stimulus that produces a response. This is a kind of associative shifting, but the response is involuntary. Terminology of Conditioning Unconditioned stimulus (US or UCS) Produces a reflexive response without learning. Unconditioned response (UR or UCR) The response that occurs, typically a reflex, involuntary and automatic. More Terminology Neutral stimulus Conditioned stimulus (CS) A stimulus not capable of producing an unconditioned response. A previously neutral stimulus that has acquired the ability to evoke a response. Conditioned response (CR) The learned response, similar to the UCR, an involuntary reflex. Two Examples http://www.youtube.com/watch?v= bOMMy1cmamE&feature=related http://www.youtube.com/watch?v= F-S2g8CXUAk&feature=related Prior to conditioning Neutral stimulus (tone) (Orientation to sound but no response) UCS (food powder in mouth) UCR (salivation) Conditioning Neutral stimulus CS (tone) + UCS (food powder) CR (salivation) After conditioning CS (tone) CR (salivation) Conditioning Processes Stimulus generalization – stimuli like the CS become able to evoke the conditioned response. Extinction – if the UCS and CS are not paired, the CS loses its ability to produce a conditioned response. Spontaneous recovery – an extinguished CS briefly returns but quickly goes away again. Acquisition, Extinction, and Spontaneous Recovery Little Albert Watson & Raynor Human fears can be acquired through Pavlovian conditioning. Rat paired with loud noise Stimulus generalized to other white objects (white rabbit, white fur coat) Mary Cover Jones developed counterconditioning -- a technique for eliminating conditioned fears. Acquisition of fear-inhibiting response Ethics of Learning Research Animals and humans are now protected by oversight and ethical guidelines. Pain or injury to animals must be weighed against and justified by the knowledge to be gained. Electric shock typically is uncomfortable and upsetting but not physically harmful. Modification of Instinctive Behavior Chapter 2 Instinctive Systems Lorenz & Tinbergen – evolution occurs when a species incorporates environmental knowledge into its genetic structure. Greylag goose and egg-rolling. Learning can sometimes modify instinctive behavior – even though the fixed action patterns are innate. Energy Model Action-specific energy builds up but is blocked (inhibited). The energy motivates appetitive (approach) behavior. Presence of a sign stimulus releases the energy by stimulating an innate releasing mechanism. The behavior occurs as a fixed action pattern (or chain of actions). Releasing Signs Releasing signs can be complex: Grayling butterfly signs include darkness of female, distance from male, and pattern of movement. Intensity of the sign influences the behavior but so does the amount of accumulated energy (time since the last response). Hierarchical System Specific behaviors are controlled by a central instinctive system. Energy can accumulate at each level in the system. Hormones generate energy. Release of energy at higher levels flows to lower levels. The sign stimulus determines which behavior will occur. Conflicting Motives If two incompatible signs appear at the same time, energy flows to a third instinct system. Stickleback fish begins nest-building when caught in a fight-flight conflict. This third behavior is called displacement. Conditioning Affects Behavior Conditioning experiences can change sensitivity to releasing signs. Only the consummatory response (eating, mating) at the end of a chain cannot be changed. Conditioning fine tunes the response to the environment and enhances survival. Criticisms of the Energy Model Best viewed as a metaphor. The brain does not literally accumulate energy in any centers and nothing flows. Willows & Hoyle – alternating contractions in sea slug allow it to escape from a starfish. Brain areas producing this response do not correspond to energy model. Acquired Changes in Response Habituation – response to a repeated stimulus decreases with experience. Sensitization – response to a repeated stimulus increases with experience. Examples: Ingestional neophobia, fear of new food Startle response Experimental Evidence Rats drink little saccharin water at first but increase over time. Loud tones (110 db) produce different responses depending on the background noise (60 vs 80 db). Habituation occurred at 60 db Sensitization occurred at 80 db A loud background is arousing, leading to greater reactivity, not less. Conditions Producing Change More intense (stronger) stimuli produce stronger sensitization, less likely to produce habituation. Greater sensitization and habituation occur when the stimulus is repeated frequently. Changes in the stimulus prevent habituation. Turkeys respond to shape changes. Conditions (Cont.) Sensitization can occur to many kinds of stimuli but habituation occurs only with innate responses. Habituation and sensitization are transient (go away after seconds or minutes between stimuli). Except long-term habituation. Dishabituation – response returns when a sensitizing stimulus occurs. Opponent-Process Theory An explanation for addictions. All experiences produce an affective reaction (pleasant or unpleasant) – called the A state. This reaction gives rise to its opposite – called the B state. B state is less intense and lasts longer. Over time, the A state diminishes and the B state increases. The Addiction Process Tolerance – diminished A state. Withdrawal – increased B state. Addictive behavior is a coping response to the change in B state. People try to enhance A state to offset the unpleasantness of the B state. Without withdrawal symptoms there is no addictive behavior. Time prevents B state strengthening. What Sustains Addiction? The B state is a non-specific aversive feeling. Anything similarly aversive will motivate the addictive behavior, even if it has no relation to the substance. Daily life stress produces a B state that results in behavior to create an A state. Parachute jumpers – create a B state in order to feel the A state.