1Chapter 7 - Operant ConditioningTheories of ReinforcementTheories of Reinforcement• In the effort to answer the question, “Whatmakes reinforcers work?”, researchers havedeveloped some theories.– Drive reduction theory– The Premack principle– Response deprivation hypothesis– Behavioral bliss point approach2Hull-drive reduction theory•If you are hungry and go looking for foodand eat some, you will feel morecomfortable because the hunger has beenreduced.• The desire to have the uncomfortable“hunger drive” reduced motivates you toseek out and eat the foodHull-drive reduction theory• Hull (1943) - Drive reduction theory– Biological needs (e.g., nutrients) lead to physiological drive states(e.g., hunger)– A stimulus acts as a reinforcer to the extent that it is associatedwith a reduction in some physiological drive (e.g., hunger, thirst,sex)– For example, food deprivation produces a hunger-drive that makesthe animal seek out food – when food is obtained the hunger isreducedExample:– If a hungry rat in a T-maze turns right and finds food, the behaviorof turning right is strengthened because it reduces the hunger-drive– Animals will repeat behaviors that produced stimuli that reducethe drive state (e.g., turning right in T-maze)3Hull-drive reduction theory• Drive-Reduction Hypothesis gave the first testablehypothesis of primary reinforcement• Accounts for a number of facts about reinforcers• Theory predicts that any stimulus that reduces drive willfunction as a reinforcer– Miller & Kessen (1952)• Trained hungry rats to go to a goal box in a T-maze• Group 1 =• Group 2 =– Results• Task learned best by drinking group – milk was a moreeffective reinforcer when they were allowed to drink it• Must be more to reinforcement than reduction of drives• This type of approach may explain some behaviors (likesex) but not others (like playing video games)Incentive Motivation• Sometimes, we just do things because theyare FUN!• When this happens, we can say thatmotivation is coming from some property ofthe reinforcer itself rather than from somekind of internal drive– Examples include playing games and sports,putting spices on food, etc.4Premack Principle• Premack (1965, 1971) – Premack Principle– We can use a behavior we love ( )to reinforce a behavior we don’t like to do very much(___________________).– Reinforcement is defined by response-basedcharacteristics not stimulus-based characteristics– Any kind of response can reinforce behavior– He argued that we have a hierarchy of behaviorsarranged according to our preference to engage in thoseactivities– Can be conditioned to elicit behaviors lower on ourpreference hierarchy if the consequence is theopportunity to engage in behaviors higher on ourpreference hierarchyPremack Principle• Premack (1959)– Observed children with free access to a candy dispenser andpinball machine to determine which behaviors were preferred– Some children preferred playing pinball to eating candy, whereasthe reverse was true for other children– Premack found that he could increase the likelihood of children’sless preferred behavior by following it with the opportunity toengage in their more preferred behavior• For example, children who preferred candy could be conditioned toplay pinball more if the reward was candy• Bobby, you can read those comic books once you have mowed thegrass!– He also demonstrated that the opportunity to perform the lessdesired response (e.g., pinball) did not function to reinforce themore desired behavior (e.g., eating candy)5Premack Principle• Premack also suggested that behavior preferences are notstatic• Preferences are influenced by:– Response deprivation (depriving the organism the opportunity ofmaking a response increases the desire of the organism to makethat response)– Response satiation (the preference for particular response can bedecrease when the response has been allowed to occur)• Response deprivation and response satiation experimentshave shown that low probability behaviors can sometimesbe used to reinforce high probability behaviors (e.g.,Mazur, 1975)• Limitation – need to know the probabilities of twobehaviors to determine whether one can be used toreinforce the otherResponse Deprivation Hypothesis• Response deprivation hypothesis– A behavior can serve a reinforcer when (1) access tothe behavior is restricted, (2) when frequency fallsbelow preferred levelExample:A rat runs in a spinning wheel for 30 mins per day (itspreferred duration of running). If running time isrestricted (e.g., 10 mins per day) it is unable to reach itspreferred duration for that activity (responsedeprivation). The rat will likely be willing to work (e.g.,lever press) to obtain more time on the running wheel.– Premack Principle – frequency of one behavior relativeto another behavior– Response deprivation –6Behavioral Bliss Point Theory• The Response Deprivation Hypothesismakes an assumption that there is anoptimal or best level of behavior that aperson or animal tries to maintain– If you could do ANYTHING at all you wantedto do, how would you distribute your time?– This would tell you your “behavioral blisspoint” for each activity or behaviorBehavioral Bliss Point Theory• Behavioral bliss point theory– If free access to more than one behavior, the organism willdistribute activities to maximise overall reinforcementExample:A rat prefers to run in a spinning wheel for 30 mins per day andexplore a maze for 1 hour per day (optimal level of reinforcement).– If performance of one activity is contingent on performance of theother, the optimum distribution may be unattainable.Example:The rat is required to do 2 minutes of spinning wheel running toreceive 1 minute of maze exploration. In this case the rat willredistribute its activities in such a way as to maximise overallreinforcement (e.g.,7Behavioral Bliss Point Theory• In other words, if you can do anything youwant, you will spend time on each thing youdo in a way that will give you the mostpleasure• This means that you can almost neverachieve your “behavioral bliss point”• So you have to compromise by coming asclose as you can, given your circumstances• Looking back on childhood--some don’twant to leave it