PSY402 Theories of LearningMidterm ResultsAnimalsAppetitive ConditioningWhat is a Reinforcer?Instrumental vs OperantSkinner’s Operant ChamberRat Operant ChamberTypes of ReinforcersTypes of Reinforcers (Cont.)ShapingExamples of Shaped BehaviorSteps in Shaping a Bar PressShaping Social BehaviorSchedules of ReinforcementInterval SchedulesRatio SchedulesDifferential ReinforcementDRH SchedulesDRL SchedulesDRO SchedulesCompound SchedulesPSY402Theories of LearningChapter 6 – Appetitive ConditioningMidterm Results{ Exam results will be available on Tuesday.Animals{ http://video.aol.com/video-detail/gregory-popovich-cutest-animal-tricks/960140359{ http://www.youtube.com/watch?v=NFg3HBMJyV4&eurl=http://rulingcatsanddogs.com/funny-pet-videos-humorous-commercials-tv-advertisements.htmAppetitive Conditioning{ Appetitive – something desirable for survival that results in approach behavior.{ Aversive – something undesirable for survival that results in avoidance or escape behavior.{ Neuroscientists believe there are underlying appetitive and aversive motivational systems in the brain.What is a Reinforcer?{ S-R learningz What is a contingency?z Thorndike’s idea of reward.{ B.F. Skinner{ Reinforcer – any response that increases the likelihood of a behavior.z Something reinforcing to one person may not be to another.Instrumental vs Operant{ Both terms refer to voluntary behavior and S-R learning.{ Instrumental conditioning –the environment limits opportunities for reward.{ Operant conditioning – no limit on the amount of reinforcement that can be earned through behavior.Skinner’s Operant Chamber{ Some behavior that can be done to obtain reward.z Rate measured by experimenter.{ A dispenser of food or liquid used as a reinforcer (reward).{ Tones or lights to signal availability of opportunity for reward.z Used in discrimination and generalization studies.Rat Operant ChamberTypes of Reinforcers{ Primary – innate reinforcing properties.z Example: something inherently pleasant such as food.{ Secondary – develops reinforcing properties through association with a primary reinforcer.z Example – money, grades, stickers.z Acquired through classical conditioningTypes of Reinforcers (Cont.){ Positive – an event added to the environment that increases likelihood of a behavior.z Example: food or money.{ Negative – termination of an aversive (unpleasant) event.z Example: headache goes away when you take aspirin.Shaping{ Shaping – Speeds up training. z Also called successive approximation procedure{ A desired behavior may occur infrequently and thus have little chance to be reinforced.{ Behaviors similar to the desired behavior are rewarded, gradually increasing the desired behavior.Examples of Shaped BehaviorSteps in Shaping a Bar Press{ Step 1 – reinforce eating from the dispenser.{ Step 2 – reinforce for moving away from the dispenser (toward bar).{ Step 3 – reinforce for moving toward the bar.{ Step 4 – reinforce for pressing the bar.Shaping Social Behavior{ Parents typically reinforce only the final response, not successive approximations.z Children may become frustrated and give up before they can obtain reward.{ Shaping techniques – start with simple behaviors a child can perform.z Gradually introduce complex behaviors.Schedules of Reinforcement{ When and how often reinforcement occurs affects learning.{ Two kinds of schedules:z When = interval schedulesz How often = ratio schedules{ Each kind of schedule can be either fixed or variable.Interval Schedules{ Fixed Interval (FI) – reinforcement is available regularly after a certain amount of time goes by.z The behavior must still be performed.z Scallop effect.{ Variable Interval (VI) – the time that must go by before reward varies.z Described as an average timeRatio Schedules{ Fixed Ratio (FR) – a specified number of behaviors must be completed before reward is given.z Post-reinforcement pause{ Variable Ratio (VR) – the number of behaviors needed to obtain reward is different each time.z Described by an averageDifferential Reinforcement{ Reward is contingent on performing the behavior within a specified period of time.z Example: due dates for class assignments{ For interval schedules, reward is also contingent on behavior but the opportunity still exists after each interval ends.DRH Schedules{ Differential reinforcement can be made contingent on a high rate of responding.{ May create a vicious circle:z Danger that the animal will give up if the high rate cannot be maintained.z If responding decreases, no reward will be obtained.z Without reward, the behavior decreases.DRL Schedules{ Reinforcement is contingent on a low rate of responding.z Animal is reinforced for withholding its behavior for a time, then showing it at the end of the period. z If a period goes by without a response then the response is shown, the reward is given.DRO Schedules{ Reinforcement is contingent on absence of a response during a specified period of time.z If a behavior is avoided entirely (e.g., hitting) then a reward is gained.{ This differs from DRL because in DRL the behavior must occur at the end of the period to gain reward.Compound Schedules{ Two or more schedules are combined.z A rat must bar press 10 times (FR-10) then wait 1 minute (FI-1) before doing another bar press to get reward.z A dog must walk across a stage, pause in front of a mirror for 2 sec, then go continue walking (TV ad){ Animals and humans are sensitive to such
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