Chapter Six

Learning

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What Is Learning?• Adaptive process through which

experience modifies pre-existing behavior and understanding.

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Adaptation to a constant stimulus is simple learning

Reponses to unchanging stimuli decreases over time.– Habituation is simplest form of learning.

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Non-Associative Learning• Learning results from the impact of one

particular stimulus.– Not the result of learning to associate one

stimulus with another (i.e. habituation.)– We learn to ignore repeated stimuli

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Another example of non-associative learning

• Why do people engage in risky behavior?

• Solomon’s (1980) Opponent Process Theory explains this – Based on disruption and restoration of equilibrium.

• Explains drug addiction, bungee jumping, and maybe even self destructive gangbanging behavior.

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Solomon’s Opponent-Process Theory

– New stimuli that cause extreme positive or negative feeling cause opposite (opponent) feeling to occur to restore equilibrium.

– If new stimulus is repeated the opponent feeling happens faster and stronger, eventually suppressing original stimulus.

– i.e. Drug addiction – over time addicts need more drug to get the same effect (habituation), and withdrawal gets worse over time too.

– i.e. Why do people skydive, ride rollercoasters?

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Most learning theories are based on associations of one stimulus with another, or associations between behavior and its consequences.

Classical Conditioning - Ivan Pavlov, John B. Watson

Instrumental & Operant Conditioning- Edward Thorndike, B.F. Skinner

Associative Learning

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Ivan Pavlov - Classical Conditioning

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Pavlov’s Classical Conditioning• Start with Unconditioned Stimulus UCS

– Causes an instinctive Unconditioned Response UCR– For example, food causes salivation (drooling)

• Then PAIR the UCS with a Neutral Stimulus– Presenting the UCS with Neutral Stimulus causes an

association to form. The more you do it, the stronger the association.

– Ex., ring a bell when you present food…– Eventually the bell ALONE will cause salivation

• The bell was neutral, but is now a Conditioned Stimulus CS which causes salivation, the Conditioned Response CR

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Classical Conditioning – UCS, UCR, CS, CR

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Apparatus for Measuring Conditioned Responses

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Little Albert – John Watson

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Changes Over Time in the Strength of a Conditioned Response: Extinction and Spontaneous

Recovery

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Stimulus Generalization - Pavlov

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Stimulus Discrimination

• What if there were no limits to stimulus generalization?

• Stimulus Discrimination: Learning to differentiate among similar stimuli.– Complementary (opposite) process to

stimulus generalization.

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Factors Affecting the Learning of a Conditioned Response

• Timing– Forward conditioning = CS then UCS

• Most effective (bell then food0

– Backward conditioning = UCS then CS• Less effective (food then bell)

– Simultaneous conditioning = Same time• Least effective (food and bell at the same time)

• Predictability• Signal Strength• Attention to Stimulus

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More Factors Affecting the Learning of a Conditioned Response

• Second-Order Conditioning– i.e. Dr.’s waiting room (cs) and shot (ucs)–

waiting room could begin to act as ucs… eventually magazines become cs.

– While adaptive, can cause problems.

• Biopreparedness– Animals are predisposed to certain

conditioning situations… perhaps genetic. – i.e. taste aversions, snakes vs. cars.

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Some Applications of Classical Conditioning

• Can play role in the development of phobias. (extreme fears that are not based on real danger or fear reactions that aren’t appropriate to real danger)– Systematic desensitization as a treatment – to cause

extinction.

• Predator Control – taste aversion• Predicting Alzheimer’s Disease – ability of

patients to be conditioned to blink (air puff = ucs, light =cs) deteriorates.

• Other applications?

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Instrumental and Operant Conditioning: Learning the Consequences of Behavior

20Continue

Edward L. Thorndike 1898

• Was studying animals’ intelligence and ability to solve problems.– Used a puzzle box.

• What were Thorndike’s cats learning?– “Law of effect” – Consequences change

behavior.– Described this kind of learning as instrumental

conditioning. – Organisms learn to do things that have satisfying or pleasurable consequences.

21Return

Figure 6.5: Thorndike’s Puzzle Box

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B. F. Skinner - Operant Cond.

• Extended and formalized many of Thorndike’s ideas.

• Organisms learn responses by operating on the environment.– “Operant conditioning”

• Primary aim was to analyze how behavior is changed by its consequences.

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Basic Components of Operant Conditioning

• Operant – a response that has an effect on the world.

• Reinforcer – a stimulus that increases the probability that the behavior which preceded it will occur again. – Positive reinforcer – a pleasurable thing follows

behavior – ie: Mom gives kid candy for good behavior in store (kid is being conditined)

– Negative reinforcer – an unpleasurable thing STOPS following behavior. ie: Kid stops whining when mom gives them candy in checkout line (mom is being conditioned)

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Figure 6.6: Positive and Negative Reinforcement

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Adapted from: The Psychology of Memory and Learning by Hintzman. © 1978 by W.H. Freeman and Company. Used with permission.

Escape Conditioning Avoidance Conditioning

Escape and Avoidance: Two types of negative reinforcement

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IMPORTANT!!• Negative reinforcement is NOT punishment.

• Negative reinforcement is the REMOVAL of unpleasant stimulus when target behavior is observed (a positive consequence of behavior – increases behavior)

• Punishment is the introduction of an aversive (unpleasant) stimulus or removal of a pleasant stimulus as a consequence of behavior – ( a negative consequence of behavior - decreases behavior.

Operant Conditioning Activity

• Two volunteers

• A bit like “hot and cold” game.

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BF Skinner 1904-1990Operant Conditioning

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Forming and Strengthening Operant Behavior

• Shaping – Process of reinforcing responses that get closer and closer to the desired response.

• Primary Reinforcer – meets basic needs i.e food, water.- Give dog a treat.

• Secondary Reinforcement– Say “good dog” when you give the dog a treat… eventually

you won’t need so many treats. (money vs. food/shelter…)– Secondary reinforcers (or “conditioned reinforcers”) – Greatly expands the power of operant conditioning.– Depends on what people like… rock concert, opera?

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Delay and Size of Reinforcement

• Timing of Reinforcer – Usually the shorter the delay between behavior and reinforcement, the more effective.

• Size of Reinforcer – Usually the larger the reinforcer, the more effective.

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Schedules of Reinforcement

• Continuous reinforcement schedule: flip switch, light goes on every time. – works well, but not practical in many situations.

• Partial or intermittent reinforcement

schedule. – also work well and more practical. Flip switch multiple times before light goes on.

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Partial / Intermittent Schedules– Fixed Ratio (FR) – every 10th response = FR10

– Variable Ratio (VR) – not as predictable, the ratio varies, but can be described as the average VR 30

– Fixed Interval (FI) – Reinforces the first response and then every fixed amount of time later as long as there is a response. (many jobs pay this way)

– Variable Interval (VI) – Random checks after some average interval has passed… avid binder check about every 2 weeks.

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Variable Interval(VI)

Variable Ratio(VR)

Fixed Interval(FI)

Fixed Ratio(FR)

Based on Number of necessary responses

Based on Time that must

first pass

Predictable

Unpredictable (“On the

Average”)

Intermittent Reinforcement Schedules

34Adapted from "Teaching Machines" by B.F. Skinner, Copyright © 1961 by Scientific American, Inc.

All rights reserved.

Effectiveness of Different Schedules of Reinforcement

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Schedules and Extinction

• Failure to reinforce a response extinguishes that response.

• Partial Reinforcement Extinction Effect– Explains why superstitious behaviors are

resistant to extinction.

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Self Stimulation – James Olds

• Pleasure Center in brain – Median Forebrain Bundle

• ..\Psych_Video_Clips\SelfStimRat_PleasureCenter.MOV

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Punishment

• Reduces the frequency of an operant behavior by presenting an unpleasant stimulus or removing a pleasant one.– Two kinds of punishment.

• Negative Reinforcement vs. Punishment– Negative reinforcement: Strengthens

behavior.– Punishment: Weakens behavior

Continue

38Return

Figure 6.10: Two Kinds of Punishment

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Potential Drawbacks of Punishment

• Does not “erase” an undesirable habit; merely suppresses it.

• Sometimes produces unwanted side effects.

• Often ineffective unless given immediately after the response and each time the response is made.

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Potential Drawbacks of Punishment (cont’d.)

• Can become aggression, even abuse, if administered in anger.

• Children are more likely to behave aggressively if frequently punished.

• Signals what is inappropriate behavior but does not specify correct alternative behavior.

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Guidelines for Effective Punishment

• Specify why punishment is being given.

• Without being abusive, punishment should be immediate and noticeable enough to eliminate the undesirable behavior.

• Identify and reinforce more appropriate behaviors.

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Cognitive Processes in Learning

• Behaviorists: Not interested in role of conscious mental activity in learning.

• Cognitive Psychologists: Learning may also result from mental processes.– Classical and operant conditioning helps to

detect causality.

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Learned Helplessness

• Tendency to give up any effort to control the environment after experience suggests that no control is possible.

• First demonstrated in animals.

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Observational Learning

• Learning by Watching Others– Also called social learning.

• Bandura’s “Bobo” Doll Experiment

• Powerful source of the socialization process.

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Bandura, A., Ross, D., & Ross, S. A. (1963). Imitation of film-mediated aggressive models. Journal of Abnormal and Social Psychology, 66, 3-11.

Observational Learning

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Main Learning Theories

• Classical Conditioning– Pairing stimuli leads to conditioned responses– Pavlov, Watson

• Operant Conditioning– Behavior is shaped by its consequences– Schedules of reinforcement – Thorndike, Skinner

• Observational Learning– People learn by watching others and observing the

consequences others receive– Bandura