Hockenbury Discovering Psychology 5th txtbk

Operant Conditioning209Shaping and Maintaining BehaviorKey Theme• New behaviors are acquired through shaping and can be maintainedthrough different patterns of reinforcement.Key Questions• How does shaping work?• What is the partial reinforcement effect, and how do the four schedules ofreinforcement differ in their effects?• What is behavior modification?operant chamber or Skinner boxThe experimental apparatus invented byB. F. Skinner to study the relationshipbetween environmental events and activebehaviors.shapingThe operant conditioning procedure ofselectively reinforcing successively closerapproximations of a goal behavior until thegoal behavior is displayed.To scientifically study the relationship between behavior and its consequencesin the laboratory, Skinner invented the operant chamber,more popularly known as the Skinner box. An operant chamber isa small cage with a food dispenser. Attached to the cage is a devicethat automatically records the number of operants made by an experimentalanimal, usually a rat or pigeon. For a rat, the typical operantis pressing a bar; for a pigeon, it is pecking at a small disk. Foodpellets are usually used for positive reinforcement. Often, a light inthe cage functions as a discriminative stimulus. When the light is on,pressing the bar or pecking the disk is reinforced with a food pellet.When the light is off, these responses do not result in reinforcement.When a rat is first placed in a Skinner box, it typically explores itsnew environment, occasionally nudging or pressing the bar in theprocess. The researcher can accelerate the rat’s bar-pressing behaviorthrough a process called shaping. Shaping involves reinforcing successivelycloser approximations of a behavior until the correct behavior isdisplayed. For example, the researcher might first reinforce the rat witha food pellet whenever it moves to the half of the Skinner box in which the bar is located.Other responses would be ignored. Once that response has been learned, reinforcementis withheld until the rat moves even closer to the bar. Then the rat mightbe reinforced only when it touches the bar. Step by step, the rat is reinforced for behaviorsthat correspond ever more closely to the final goal behavior—pressing the bar.Skinner believed that shaping could explain how people acquire a wide variety ofabilities and skills—everything from tying shoes to operating sophisticated computerprograms. Athletic coaches, teachers, parents, and child-care workers all useshaping techniques.The Skinner BoxPopularly called aSkinner box afterits inventor, anoperant chamber isused to experimentallystudy operantconditioning inlaboratory animals.(a) (b) (c)Operant Conditioning at Sea-World This sequence shows a Sea-World trainer using operant conditioningprinciples with a dolphinthat has already been shaped toperform somersaults. (a) Thetrainer gives the dolphin two discriminativestimuli—a distinct vocalsound and a specific hand gesture.(b) The dolphin quicklyresponds with the correct operant—aperfect somersault in theair. (c) The operant is positively reinforcedwith a piece of fish. Thesame basic techniques are alsoused to teach seals, sealions, walruses, and killer whalesto perform different tricks on cue.