1) The process of building an operant by reinforcing only those responses that are closest to it. When the operant we want is a response to a certain kind of stimulus (such as answers to a question or solutions to problems) , shaping also requires "building" in the stimuli to be presented. The first questions or problems given to students are not as complex as those we expect them to answer or solve later.

2) The use of differential reinforcement on a series of successive approximations to a target behavior.

"3) Teaching new behaviors by systematically reinforcing successive approximations toward the behavioral objective. Sometimes PSI or individualized instruction is referred to as shaping.

4) The method of successive approximation or shaping may be used to establish a response. This method involves the reinforcement of closer and closer approximations to the final performance. For example, a rat may be reinforced for standing in the vicinity of a lever. Once the animal is reliably facing the lever, a movement of the head toward the bar is reinforced. Next, closer and closer approximations to pressing the lever are reinforced. Each step of the procedure involves reinforcement of closer approximations and nonreinforcement of more distant responses. Many novel forms of behavior may be shaped by the method of successive approximation."

5) The reinforcement of successive approximations of a target behavior.

6) Gradually modifying some property of responding (often but not necessarily topography) by differentially reinforcing successive approximations to a target operant class. Shaping is used to produce responses that, because of low operant levels and/or complexity, might not otherwise be emitted or might be emitted only after a considerable time. The variability of responses after one response has been reinforced usually provides an opportunity to reinforce a response that still more closely approximates the criteria that define the target operant class. Shaping is therefore a variety of operant selection.