Hockenbury Discovering Psychology 5th txtbk

210 CHAPTER 5 LearningSuperstitious Rituals: Behaviors Shaped byAccidental Reinforcement Many professionalathletes develop quirky superstitiousrituals (Wargo, 2008). Pittsburgh Steelersquarterback Ben Roethlisberger was sodepressed after losing an im portant gamethat he didn’t bother to shave. But after anunshaven Roethlisberger won the nextgame, he decided that the beard was agood luck charm. After five months of winninggames, a still-unshaven Roethlisbergerled the Steelers to a Super Bowl victory.One night later, an elated Roethlisbergercelebrated by publicly shaving his beard onDavid Letterman’s Late Show.Skinner (1948b) pointed out thatsuperstitions may result when a behavior isaccidentally reinforced—that is, when reinforcementis just a coincidence. So althoughit was really just a fluke that wearing your“lucky” shirt or playing your “lucky” numberwas followed by a win, the illusion ofreinforcement can shape and strengthenbehavior.continuous reinforcementA schedule of reinforcement in which everyoccurrence of a particular response isreinforced.partial reinforcementA situation in which the occurrence of aparticular response is only sometimesfollowed by a reinforcer.extinction (in operant conditioning)The gradual weakening and disappearanceof conditioned behavior. In operant conditioning,extinction occurs when an emittedbehavior is no longer followed by areinforcer.partial reinforcement effectThe phenomenon in which behaviors thatare conditioned using partial reinforcementare more resistant to extinction than behaviorsthat are conditioned using continuousreinforcement.schedule of reinforcementThe delivery of a reinforcer according toa preset pattern based on the number ofresponses or the time interval betweenresponses.fixed-ratio (FR) scheduleA reinforcement schedule in which a reinforceris delivered after a fixed number ofresponses has occurred.The Partial ReinforcementEffectBuilding Resistance to ExtinctionOnce a rat had acquired a bar-pressing behavior,Skinner found that the most efficientway to strengthen the response wasto immediately reinforce every occurrenceof bar pressing. This pattern of reinforcementis called continuous reinforcement.In everyday life, of course, it’s commonfor responses to be reinforced onlysometimes—a pattern called partial reinforcement.For example, practicing yourbasketball skills isn’t followed by puttingthe ball through the hoop on every shot.Sometimes you’re reinforced by making abasket, and sometimes you’re not.Now suppose that despite all your hard work, your basketball skills are dismal. Ifpracticing free throws was never reinforced by making a basket, what would you do?You’d probably eventually quit playing basketball. This is an example of extinction.In operant conditioning, when a learned response no longer results in reinforcement,the likelihood of the behavior’s being repeated gradually declines.Skinner (1956) first noticed the effects of partial reinforcement when he beganrunning low on food pellets one day. Rather than reinforcing every bar press, Skinnertried to stretch out his supply of pellets by rewarding responses only periodically.He found that the rats not only continued to respond, but actually increased theirrate of bar pressing.One important consequence of partially reinforcing behavior is that partiallyreinforced behaviors tend to be more resistant to extinction than are behaviorsconditioned using continuous reinforcement. This phenomenon is called the partialreinforcement effect. For example, when Skinner shut off the fooddispensingmechanism, a pigeon conditioned using continuous reinforcementwould continue pecking at the disk 100 times or so before the behavior decreasedsignificantly, indicating extinction. In contrast, a pigeon conditioned with partialreinforcement continued to peck at the disk thousands of times! If you thinkabout it, this is not surprising. When pigeons, rats, or humans have experiencedpartial reinforcement, they’ve learned that reinforcement may yet occur, despitedelays and nonreinforced responses, if persistent responses are made.In everyday life, the partial reinforcement effect is reflected in behaviors that persistdespite the lack of reinforcement. Gamblers may persist despite a string of losses,writers will persevere in the face of repeated rejection slips, and the family dog willcontinue begging for the scraps of food that it has only occasionally received at thedinner table in the past.The Schedules of ReinforcementSkinner (1956) found that specific preset arrangements of partial reinforcementproduced different patterns and rates of responding. Collectively, these differentreinforcement arrangements are called schedules of reinforcement. As we describethe four basic schedules of reinforcement, it will be helpful to refer to Figure 5.6,which shows the typical pattern of responses produced by each schedule.With a fixed-ratio (FR) schedule, reinforcement occurs after a fixed numberof responses. A rat on a 10-to-1 fixed-ratio schedule (abbreviated FR-10) wouldhave to press the bar 10 times in order to receive one food pellet. Fixed-ratioschedules typically produce a high rate of responding that follows aburst–pause–burst pattern. In everyday life, the fixed-ratio schedule is reflected