Learning. Stimulus Behavior Mental Processes Behaviorism Psychology is the “science of behavior.” Emphasis on what can be directly observed. Ignore the

LearningLearning

Learning

Stimulus Behavior

Mental Processes

BehaviorismPsychology is the “science of behavior.”

Emphasis on what can be directly observed. Ignore the mind (unobservable).

Emphasis in Reinforcements / Rewards

(Response)

B. F. Skinner

Classical conditioning

Ivan Pavlov (early 1900s)

• Russian physiologist

• Nobel prize winner for his work on the digestive system

» Interested in the salivary reflex

» Do different types of food elicit different amount of saliva?

http://www.mphy.lu.se/avd/nf/hesslow/bilder/pavlov.jpg


Food Salivation

Footsteps

Food bowl

Bell

Salivation

Reflex

Not ReflexLearned behavior!


How does classical conditioning work?

Step 1: Find a stimulus that elicits a reflexive behavior

Step 2: Pair stimulus with a neutral stimulus that does not normally elicit the same reflexive behavior

Step 3: Over time, if neutral stimulus always signals the original stimulus, the previously neutral stimulus will now elicit the reflexive behavior

Stimulus(i.e., food)

Reflexive response(i.e., salivation)

Neutral Stimulus(i.e., bell)


Stimulus(i.e., food)

Reflexive response(i.e., salivation)

Neutral Stimulus(i.e., bell)

Food — Unconditioned stimulus (UCS)

Salivation — Unconditioned response (UCR)

Bell — Conditioned stimulus (CS)

Salivation (in response to bell) — Conditioned response (CR)


What are the requirements for classical conditioning to work?

• The conditioned stimulus (i.e., bell) must be previously neutral

• Contiguity during acquisition

» the CS must come immediately before the UCS

» The CS should signal the UCS

• Contingency

» If the CS no longer signals the UCS reliably, the CR will stop (i.e., extinction)

• Spontaneous recovery

» Even after extinction, it is possible to re-establish the CS - CR relationship

If all of these conditions are followed, any neutral stimulus has the potential to become a conditioned stimulus


Different stages of classical conditioning


Little Albert (8-month old infant)

Stimulus(i.e., loud noise)

Reflexive response(i.e., startled & cry)

Neutral Stimulus(i.e., white rat)

Stimulus generalization

• Previously neutral stimuli that are similar to the CS will now elicit the CR

Click here for video


Classical conditioning in humans

“Give me a dozen healthy infants, well formed, and my own specified world to bring them up in and I’ll guarantee to take any one at random and train him to become any type of specialist I might select —doctor, lawyer, artist, merchant-chief, and yes, even beggar-man and thief, regardless of his talents, penchants, tendencies, abilities, vocations and race of his ancestors.”

- John B. Watson, 1924, Behaviorism

What a freak!


Application of classical conditioning theories: Drug addiction

Stimulus(i.e., drug)

Reflexive response(i.e., physiological response)

Neutral Stimulus(i.e., needle, back alley)


But ... classical conditioning doesn’t explain all learning

• Not all unconditioned stimuli are equal

» Some fears are easier to condition than others

• Does not account for reward and punishment

http://www.theage.com.au/ffximage/2007/04/16/snake,0.jpg; http://www.sunbeamhospitality.com/resources/images/products/3278-500-600/3278int_xlg.jpg

Operant conditioning

Operant (instrumental) conditioning

• All actions serve some purpose

• We learn to behave in a certain way because those behaviors lead to rewards

• We learn NOT to behave in a certain way because those behaviors lead to punishment (or no reward)

• Consequences matter



Reward Increase in behavior

Punishment(or no reward) Decrease in behavior

Activates reward system (n. accumbens)


B. F. Skinner

• The organism behaves in a certain way in order to change the environment

» not merely a passive recipient of the conditioned stimulus

» behaviors repeat because they have been reinforced

» consequence of behavior matters

http://www.bfskinner.org/images.asp

Operant conditioningReinforcement — a positive consequence that follows a behavior

Punishment — a negative consequence that follows a behavior

Likelihood to repeat behavior

Cha

nge

in e

nviro

nmen

t

increase

reinforcement

reinforcement

decrease

punishment

punishmentpositive

stimulus

added

positive

negative

stimulus

removed

negative

(get to use car more often)

(no longer dependent on

parents)

(additional hassle)

(take away driving

privileges)


How to measure effects of reinforcement/punishment?

http://www.cs.tcd.ie/research_groups/crite/personal/imgs/skinner3.gif

Likelihood to repeat behavior

Cha

nge

in e

nviro

nmen

t

increase decrease

positivereinforcementstimulus

added

stimulus removed

negativereinforcement

positivepunishment

negativepunishment

(water)

(foot shock removed)

(foot shock introduced)

(water removed)

Operant conditioningHow do you get the animal to do what you want to begin with?

• Shaping

» Successive approximation — reward behavior that is similar to the desired behavior

Desired behavior Pressing lever

Initial behavior Sitting

Standing

Standing on hind legs

Standing near lever

Sniffing lever

Operant conditioningWhat does it take for operant conditioning to work?

• Reinforcers must be presented immediately after the behavior

» Primary reinforcer — fulfills basic needs (e.g., food, water)

» Secondary reinforcer — more abstract (e.g., money, fame)

• Delivery of the reinforcer must be consistent

Operant conditioningHow often should a reinforcer be given?

Reinforcement schedules

continuous reinforcement(i.e., desired behavior is

reinforced every time)

partial reinforcement(i.e., desired behavior is

reinforced intermittently)


Reinforcement schedule

Partial reinforcement

Ratio Interval

Fixed Variable Fixed Variable

RatioInterval

Fixed

Variable

every 5th lever press every 20 seconds

3rd, 8th, 19th, 20th, 35th 2s, 8s, 34s, 36s, 40s

Predictable

Unpredictable

Operant conditioningHow is behavior influenced by the different schedules?

Casinos use variable ratio reinforcement

Limitations of conditioning theories

But ... conditioning theories do not explain all learning

• One trial learning: taste aversion

» A rat given sweetened water before radiation (which causes nausea) will later avoid

sweetened water, even after just one exposure

• Insight learning» Kohler’s experiment

Video _pigeon

http://www.youtube.com/watch?v=mDntbGRPeEU

Figure 6.6

But ... conditioning theories do not explain all learning

• Remember ... Skinner claimed that learning is a result of reinforcement

• If that’s true, then unreinforced behaviors should not be learned

» Latent Learning (Edward Tolman)

» Trained rats to run mazes

» Will rats learn without reinforcements?


Latent learning: Will rats learn without reinforcements?

• Train rats to run a maze under 3 conditions:

» continuous reinforcement

» no food reward until the 11th day

» no food reward ever


http://psychclassics.yorku.ca/Tolman/Maps/FIG1.gif

Remember, conditioning theories state that ...

• Reinforcement is necessary for learning to occur

Latent learning


No food

No food (first 10 days)

Continuous food

No food

No food (first 10 days)

Continuous food

Learning took place even when there was no reinforcement

Learning was revealed after behavior was reinforced

Learning through observation (in humans):

• Albert Bandura’s Bobo doll experiment


Bobo dollhttp://academic.evergreen.edu/h/hiljus01/bobo.gif

Results:

Children who observed violent adult interactions

with bobo doll displayed more aggressive

interactions with the doll than children who

observed non-violent adult interactions with doll

Observational learning video

http://www.youtube.com/watch?v=2l4hGvSIZSA

Learning through observation (in monkeys):

• Monkeys raised in the lab environment did not show fearful responses towards snakes

• Shown footage of other monkeys being fearful of snakes

• Monkeys raised in lab developed a fearful response towards snakes


Conditioning: Phobias- overgeneralization: a dog bit me -> afraid of all dogs afraid of animals afraid of going outside

- role of classical conditioning: CS (dog), US (dog bite) UR (pain, fear)

=> CS (dog) – fear response;

role of operant conditioning: avoid CS (dog) reduces anxiety => continue avoiding CS

- treatment: pair fear stimuli with relaxation (or other pleasurable stimuli)

other things: fear of some stimuli (snakes, heights, dark) more common than others (knives, electrical outlets): argues against equipotentiality, in favor of evolution

-illusory correlation between feared stimulus and negative outcome

Conditioning: Physical punishment by parents

- Should we use punishment to eliminate unwanted behavior? No.

but if you do, do immediate punishment (more effective than delayed punishment, this is true even for your pets!)

Why not use punishment?- more punishment => more aggressive behavior by the child

=> child likely to use physical punishment when he grows up

Does punishment really cause aggression?

Alternatives hypotheses:

- aggression causes punishment

- a third variable (e.g., genetics) causes aggression & punishment

External vs. Intrinsic rewards

Nursery school children

Paper & crayons: draw whatever you want

External reward group: “Good Player Award”

Intrinsic reward group: nothing

External reward increased amount of time drawing, BUT

Ending external reward reduces drawing time below the intrinsic reward group!

should we give students extra-credit for attending talks in their major?

Lepper & Greene, 1978

Operant Conditioning: Infant sleep

Infant Sleep

Extinction is harder to achieve after intermittent reward (partial reinforcement)

- baby cries, dad breaks down and goes in to console the baby:

- baby learns that crying leads to reward (daddy comes)

- to make matters worse, dad only breaks down sometime (partial reinforcement)

Operant Conditioning: other applied issues

- ‘variable ratio’ reinforcement also occurs in casinos

-Operant conditioning is used

- to train animals (flipper, sea world)

- for Token economies in psychiatric hospital: target behavior, reinforcers (sometimes fail to transfer to outside world)

- in Applied behavioral analysis (for autism)

- for Behavior modification (kazdin, slate)

http://www.slate.com/id/2188744/

Take home message


• Association between neutral and reflexive stimuli leads to learning

• Passive process


• Consequences matter

• Takes rewards and punishments into account

• Active engagement with the environment

Limitations to conditioning theories:• Not all unconditioned stimuli are the same

• One-trial learning

• Insight learning

• Latent learning

• Learning through observation

Other things to include:

Classical conditioning example: baby bottle suck

Species specific behavior: racoons & pigs

Figure 6.11

Figure 6.12

Documents

Learning. Stimulus Behavior Mental Processes Behaviorism Psychology is the “science of behavior.” Emphasis on what can be directly observed. Ignore the