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• Please write down your homework:– Test next class. Ch. 8 and all review chapters– Notecards due next class

Operant ConditioningOperant Conditioning

IntroductionIntroductionClassical Conditioning= an organism

associates different stimuli that it does not control.

Operant Conditioning= the organism associates its behaviors with consequences. Behaviors followed by reinforcements increase; those followed by punishers decrease.

Operant means…Operant means…

….Explain and train

Operant ConditioningOperant Conditioning•A type of learning in which

responses can be controlled by their consequences

i.e. rewards or

punishments

Reward vs. PunishmentReward vs. Punishment

Reward = more likely behavior will repeat

Punishment = less likely to repeat behaviors

BehaviorBehavior

• Respondent Behavior

– Behavior that occurs as an automatic response to some stimulus

Ex: food when hungry; water when thirsty

• Operant Behavior

– The act operates on the environment to produce rewarding or punishing stimuli

Ex: good grades = MONEY; bad grades = grounded

Important People in Operant Conditioning

B.F. Skinner

Edward Thorndike

Radical Behaviorism

Skinner BoxPuzzle Box

Law of Effect

SkinnerSkinner• Operant Chamber-

– “Skinner Box”– Soundproof– Bar or key that an animal presses or pecks to

release a rewards of food or water– Device that records these responses

• Shaping-- Procedure in which reinforcers (like food) gradually guide an animal’s actions toward a desired behavior

Edward L. ThorndikeEdward L. Thorndike• Law of Effect:

– Rewarded behavior is likely to reoccur– Puzzle Box

Operant Conditioning Chamber

Skinner BoxSkinner Box

Puzzle BoxPuzzle Box

Two important concepts used in Operant Two important concepts used in Operant ConditioningConditioning

• Reinforcer - (Positive and Negative)Reinforcer - (Positive and Negative)– A stimulus or event that increasesincreases the odds of repeating the

behavior that led to it I give my kids money when they clean their room…this stimulus increases the odds they will do it again

• PunisherPunisher– A stimulus or event that functions to decreases the odds of

repeating the behavior that lead to I spank my kids when they throw food at the dinner table…this event decreases the odds they will do it again

Remember…Remember…– It is often the learner that determines if something is a

reinforcement or punishment– This is called the Premack PrinciplePremack Principle

Example: I might give Ryan broccoli after he did a chore and if he likes it he will do more chores or I might give Ryan broccoli after he did a chore and he may never do that chore again. My feelings toward broccoli make no difference

Reinforcer

Two Types of Reinforcement:Positive and Negative

Anything likely to increase a behaviorAnything likely to increase a behavior

Positive Reinforcement

• Something desirable is addedadded to the environment and this encourages (reinforces)(reinforces) behavior– Behaviors are strengthened when they are followed

by the introduction of a stimulus

AA

Negative Reinforcement• Something undesirable is subtractedsubtracted from the

environment and this encourages (reinforces)(reinforces) behavior– NR are aversive stimuli such as loud noise, cold, pain, or

nagging• We are more likely to repeat behaviors that lead to their removal

– Example• Say I have a headache• The NR is the pain of the headache• I take aspirin and the headache goes away• Headache pain (stimulus) - - aspirin (response) - - consequence

(headache gone)• I will take aspirin again because it removed something unpleasant

So…positive and negative do not mean good or bad. So…positive and negative do not mean good or bad. Instead, positive means Instead, positive means addingadding a stimulus, and a stimulus, and

negative means negative means removingremoving a stimulus. a stimulus.

Types of Reinforcers

Types of ReinforcersTypes of Reinforcers

• Primary Reinforcers- reinforcements that happen naturally; not learned (i.e. getting food when hungry, taking your hand off a burning stove to relieve pain)

• Conditioned Reinforcers- (secondary reinforcers) are learned. (i.e. if a rat in Skinner’s box learns that when a light signal goes off it signals food, the light becomes on the secondary reinforcer

Primary Reinforcer• Things that are in themselves rewarding and

satisfy biological needs

• Like food, warmth, or water

Secondary (or Conditioned) Reinforcer

• Something that you have learned to value through classical conditioning – Money, fines or grades

• Secondary reinforcers can loose their effectiveness

Reinforcement Schedules

The pattern (schedule) in which reinforcement (reward or

punishment) is given.

These schedules influence learningThese schedules influence learning

Continuous Reinforcement

• Reinforcing the desired response every time it occurs.– Example – vending machine

Quick Quick AcquisitionAcquisition

Quick Quick ExtinctionExtinction

Partial Reinforcement• Reinforcing a response only part of the time.Reinforcing a response only part of the time.

– slot machine– You don’t expect to win every

time but hope to win sometime– The acquisition process is slower, but… – Greater resistance to extinction.

• 4 different partial reinforcement schedules

– Two focus on timetime between reinforcement (interval (interval schedule)schedule)

– Two focus on numbernumber of responses between

reinforcement (ratio schedule)(ratio schedule)

Fixed-Interval ScheduleFixed-Interval Schedule

• Reinforcement of a behavior after a specified or fixed time (interval)time (interval) has passed.

• You get paid every two weeks

• A worker gets a bonus once a year– After receiving a reward (a reinforcement)

the worker has to wait one year for another reward (fixed interval)

Variable-interval Schedule• Reinforcement of a behavior

at unpredictable (variable) timetime intervals.

• You don’t know when the reinforcement is coming so you keep trying or have to be prepared to take action

Pop Quizzes

Fixed-ratio Schedules

• Reinforcement of a behavior only after a specified (fixed) numbernumber of responses

• Movie rentals that say rent 5 get one free

• A worker gets a bonus after every three items he sells

Variable-ratio Schedule• Reinforcement of a behavior after an

unpredictable (variable) number number of responses.– Working on sales commission

• Sometimes called the gambler’s schedulegambler’s schedule– Back to the lottery…– You don’t know when you will win but you do

know the more you buy the better your chances

Overjustification EffectOverjustification Effect• When external rewards undermine the intrinsic

satisfaction of performing a behavior – Makes people only do something for reward or prize

and not for pure joy– Usually the reward may lesson and replace the

person’s original, natural motivation so that the behavior stops if the reward is eliminated

• Pizza for reading– “what, I don’t get a free pizza for reading 10

books?”

PunishmentPunishment• Flip side of reinforcement• The introduction of a bad

stimulus or the removal of a reinforcing stimulus after a response occurs– Weakens a behavior or makes it

less likely to occur again in the future

Does punishment Does punishment work?work?

Yes, Yes, but…but…Often tells the learner what behavior should NOT be

exhibited and not what behavior should be

And…don’t forget the Premack Principle

Difference between Negative Difference between Negative Reinforcement and PunishmentReinforcement and Punishment

Punishment Punishment the introduction of a negative consequence the introduction of a negative consequence

after a behavior weakens the behaviorafter a behavior weakens the behavior Time out for hitting other childrenTime out for hitting other children

Negative ReinforcementNegative Reinforcement the removal of a negative stimulus after a the removal of a negative stimulus after a

behavior strengthens the behaviorbehavior strengthens the behavior Picking up a crying babyPicking up a crying baby