Module 18

Classical Conditioning (cont’d)

Processes of Conditioning ƒ Acquisition ƒ Extinction ƒ Spontaneous Recovery ƒ Stimulus Generalization/ Discrimination

Spontaneous recovery

™ The re-emergence of an extinguished CR after a period of rest Classical Conditioning

ƒ Generalization ƒ tendency for stimuli similar to CS to elicit similar responses ƒ Can be adaptive- as children taught to fear moving cars on street to respond similarly to trucks and motorcycles on the street ƒ Discrimination ƒ in classical conditioning, the learned ability to distinguish between a CS and other stimuli that do not signal a US ƒ E.g., fear pitbulls but not golden retrievers ƒ Lightning but not flashing disco lights

Updating Pavlov’s understanding ƒ Role of mental processes ƒ Thought/expectation of the CS-US link matters for conditioning ƒ Consistent link between the CS and US matters ƒ Role of biological dispositions ƒ Each species’ biological dispositions prepare it to learn the associations that enhance its survival ƒ Taste aversion (rather than sight) in rats - they are biologically prepared to learn associations between the taste of a particular food and the onset of an illness, but not between sights and sounds and an illness.

Classical Conditioning: Key Points

ƒ CC prepares us for significant events by identifying events that commonly predict them ƒ Can explain a wide range of behavior ƒ Advertising, food aversion, phobias ƒ Focuses on naturally occurring responses ƒ Not under voluntary control ƒ Any naturally occurring behavior (or response) can be conditioned to neutral stimulus ƒ Eye blink — bell ƒ Sexual arousal — perfume How far does the power of CC spread?

™ Pictures rates as similar / neutral by a group of judges ™ Then these faces were presented to a new group – each picture was paired with either a pleasant, neutral, or unpleasant odor. ™ When later asked to evaluate the faces the subjects the highest ratings were given to those pictures that had been associated with the pleasant odor. ™ The lowest ratings were given to those pictures which had been paired with the unpleasant odor (Todrank, Byrnes, Wrzesniewski, & Rozin, 1995)

Module 19 - Operant Conditioning

Learning that behaviors are associated with their consequences

Operant Conditioning ƒ Behaviors are associated with their consequences ƒ Learning in which behavior [operant] is strengthened if followed by a reinforcer and weakened if followed by a punisher ƒ What is a reinforcer? ƒ What is a punisher? Important: Reinforcers and punishers are defined by their effects on behavior, not by your intentions

™Example: Ali is acting out while his mother is watching Seda Sayan show. His mother turns around and tells him to stop, but Ali increases the noise he makes. His mother scolds him. Ali becomes even more active and louder. His mother spanks him, and Ali starts shouting and jumping up and down on the sofa.

History of Operant Conditioning: Thorndike’s (early 20th century) Law of Effect ƒ Behaviors followed by favorable consequences become more likely, and behaviors followed by unfavorable consequences become less likely

Thorndike's Law of Effect

Good Strengthens Outcome

Behavior

Weakens Bad Outcome Skinner’s (late 20th century) behavioral technology

ƒ Operant chamber / Skinner box

ƒ Using behavioral technology, Skinner could teach pigeons to walk on a figure 8, play ping pong, or play simple computer games

How to strengthen behavior: Reinforcement ™Provide a reward = positive stimulus ƒ If presented AFTER a response, it strengthens the response ƒ E.g., food, pleasurable sensation, … ™Take away something that is undesirable or unpleasant = reduce negative stimulus ƒ If removed AFTER a response, it strengthens the response ƒ E.g., A whining child being quiet, seat belt warning sound not beeping, alarm clock going quiet

Reinforcer

ƒ any event/stimulus that strengthens, or increases the likelihood of a prior response. ƒ Two kinds: ƒ Positive reinforcer: presentation of a positive stimulus ƒ Negative reinforcer: removal of a negative stimulus Types of Reinforcers

™Primary Reinforcer ƒ innately satisfies a biological need ƒ Food, security, positive feelings ™Conditioned (secondary) Reinforcer ƒ stimulus that is reinforcing because it is associated with a primary reinforcer ƒ Money, good grades, words of praise, pleasant tone of voice

In real life we are not continuously and immediately reinforced. ƒ Immediate reinforcers are the only ones that work with most animals. ƒ Humans do respond to delayed outcomes. ƒ E.g. Good grades at the end of the semester ƒ E.g. Salary at the end of the month ƒ Requires requires cognitive engagement.

ƒ People may need to choose between immediate – smaller consequences & delayed- bigger consequences. ƒ Chocolate cake now – or losing weight in a month. ƒ Smoking now – lung cancer in 30 years?

Schedules of Reinforcement

ƒ Continuous Reinforcement ƒ reinforcing the desired response each time it occurs ƒ learning occurs rapidly ƒ Partial (Intermittent) Reinforcement ƒ reinforcing a response only part of the time ƒ results in slower acquisition but greater resistance to extinction ƒ can be rewarded based on frequency of behavior (fixed ratio or variable ratio) ƒ can be rewarded based on the time interval (fixed interval or variable interval) Vary number of responses required ™Fixed Ratio Schedule: reinforces a response after a specified number of responses ƒ faster you respond the more rewards you get (e.g. piecework pay, frequent flyer programs) ƒ very high rate of responding because resting reduces rewards ™Variable Ratio Schedule: reinforces a response after an unpredictable number of responses ƒ very hard to extinguish because of unpredictability ƒ very high rate of responding because resting reduces rewards (e.g. gambling, fishing)

Vary time of interval ™Fixed Interval: reinforces a response after a specified time has elapsed ƒ response occurs more frequently as the anticipated time for reward draws near (e.g. Monthly payments, checking to see if the cake is baked, studying hardest before the mid term) ™Variable Interval: reinforces a response at unpredictable time intervals ƒ produces slow steady responding (e.g. pop quiz, checking for email from a loved one)

Schedules of Reinforcement

Number of responses Fixed Ratio 1000 Variable Ratio

750 Fixed Interval Rapid responding near time for 500 reinforcement Variable Interval

250

Steady responding 0 10 20 30 40 50 60 70 80 Time (minutes) How to weaken a behavior: Punishment ™A punisher decreases the frequency of the preceding behavior ƒ An unpleasant or undesirable stimulus will powerfully reduce unwanted behavior ™How can we punish? ƒ Positive punishment: Provide an unwanted stimulus ƒ Negative punishment: Take away a desired or wanted stimulus

Teaching complex behaviors: Shaping ™A procedure in which reinforcers guide behavior towards gradually closer approximations of the desired behavior. ƒ Build on existing behaviors that occur by chance ƒ Make rewards contingent on closer approximations

Operant vs Classical Conditioning