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Instrumental Conditioning

Instrumental Conditioning

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Instrumental Conditioning

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  1. Instrumental Conditioning Also called Operant Conditioning

  2. Pavlovian Conditioning = Stimulus learning Instrumental Conditioning = Response learning Instrumental behavior = behavior that occurs because it was previously instrumental in producing certain consequences Also called ‘goal-directed’ behavior

  3. Early work in this area done by Thorndike (late 1800s) • put cats in puzzle boxes • the cats had to manipulate a latch to open the door, escape and get food • initially the cats would thrash about randomly until they accidentally opened the door • then the latency to escape and get food would decrease over successive trials

  4. The behavior, or response, is instrumental in, or responsible for, the outcome (i.e., escaping and getting food). Thus, this type of learning became known as ‘instrumental conditioning’

  5. Thorndike interpreted the results of his experiment as reflecting the learning of an S-R association Thorndike believed the cats learned an association between the stimuli inside the puzzle box and the escape response The consequence of the successful response – escaping the box – strengthened the association between the box stimuli and that response On the basis of his work, Thorndike formulated the law of effect

  6. Law of effect • this law states that if a response in the presence of a stimulus is followed by a satisfying event, the association between the stimulus (S) and the response (R) is strengthened • if the response is followed by an annoying event, the S-R association is weakened • according to the law of effect, animals learn an association between the response and the stimuli present at the time of the response – the consequence of the response is not one of the elements in the association • the satisfying or annoying consequence simply serves to strengthen or weaken the association between the response and the stimulus situation

  7. Modern approaches to the study of Instrumental Conditioning Discrete-Trial Procedures • involves a single response performed only at a certain time • rat is put in start arm and runs to goal arm where it receives food • only single action (or response sequence) and reward is given • then rat removed from the apparatus • after ITI the animal is placed in the start arm again for another trial • each response is a discrete action. The speed and onset of the behavior is determined by the subject. The experimenter determines when the subject may begin the action (usually by putting the rat in the start arm)

  8. Modern approaches to the study of Instrumental Conditioning Free-Operant Procedures • more like what you will do in the lab with bar-pressing • here the experimenter decides which behavior is correct but the subject determines when the behavior will be executed • your rats will be put in an operant chamber and allowed to respond at their own pace • subjects can make the response and receive reward more than once • an operant response (such as a bar-press) is defined in terms of the effect that it has on the environment – the critical thing is not the muscles involved in the behavior but the way in which the behavior ‘operates’ on the environment

  9. Cumulative Recorder

  10. Cumulative Record • way of presenting data in free-operant procedures • one response builds on the previous response Response Measures • with discrete-trial procedures can measure speed, and latency to make the response • with free-operant procedures can measure rate of responding (#BP/min)

  11. Studies can also combine elements of both discrete-trial and free-operant procedures For ex., L tells subject when to respond and the subject can then respond at its own pace Responses are freely emitted by the subject, but some control by the experimenter

  12. Magazine Training and Shaping • in order for instrumental conditioning to occur, the subject must make the desired response prior to receiving the reward • how do we train rats to make the response (i.e., bar-press)? • the preliminary phase is called magazine training • the food-delivery device is called the food magazine • when food is delivered the device makes a noise • after enough pairings of this noise with food • delivery, the rat will go to the food cup when it hears • the noise

  13. Magazine Training and Shaping • after magazine training, the animal is ready to learn the instrumental response • we ‘teach’ the response through a process called response shaping • shaping involves: • reinforcement of successive approximations to the • required response • and nonreinforcement of earlier response forms

  14. Instrumental Conditioning Procedures There are 4 basic types of instrumental conditioning These 4 types are categorized according to: 1. Nature of the outcome controlled by the behavior a. Appetitive stimulus – pleasant outcome (food) b. Aversive stimulus – unpleasant outcome (shock) 2. Relationship or contingency between the response and the outcome a. Positive contingency – R produces O b. Negative contingency – R eliminates/prevents O

  15. Instrumental Conditioning Procedures

  16. Instrumental Conditioning Procedures 1. Positive reinforcement – also called reward training • response produces an appetitive outcome that is not • as likely to occur otherwise • positive contingency between the response and an • appetitive stimulus • example, rat bar-press for food • result: response increases

  17. Instrumental Conditioning Procedures 2. Punishment • positive contingency between the response and an • aversive stimulus • if the subject performs the response, it receives the • aversive outcome • if the subject does not perform the response, it does • not receive the aversive outcome • example, shock a rat whenever it makes a BP • or mother scold child for playing in the street • result: response decreases

  18. Instrumental Conditioning Procedures 3. Negative reinforcement • negative contingency between the response and an • aversive stimulus • the response terminates or prevents the delivery of • an aversive stimulus • example, put a rat in a box and give him continuous • shocks. The rat could jump over a barrier to turn off • or escape the shock. • this is called an escape procedure • subjects can also avoid an aversive stimulus that is • scheduled to occur

  19. Instrumental Conditioning Procedures 3. Negative reinforcement (Escape/Avoidance) • example, students can study before an exam to avoid • getting a bad grade • example, a rat may be scheduled to receive a shock • at the end of a warning stimulus. If he makes a certain • response (BP or jump over a barrier) before the • warning stimulus is over, he avoids getting shocked • result: response increases

  20. Instrumental Conditioning Procedures 4. Omission Training • negative contingency between the response and an • appetitive stimulus • the response prevents the delivery of a pleasant • event • if the subject does not make the response, the reward • is delivered • example, a child is told to go to his room when he does • something bad • example, suspending someone’s driver’s license for • impaired driving • result: response decreases

  21. Instrumental Conditioning Procedures 4. Omission Training • usually with omission training, the subject can receive • the reward for engaging in other behaviors • sometimes referred to as DRO • Differential Reinforcement of Other behaviors