shaping

Shaping is a method for producing a desired behavior or form by reinforcing successive approximations toward the target. The concept is central to operant conditioning and has wide application in psychology, education, and animal training. It originated in the work of B. F. Skinner, who used it to guide animals through complex chains of responses.

In practice, shaping begins with an initial behavior the subject can perform reliably. The trainer reinforces that behavior, then introduces a slight variation that more closely resembles the target and reinforces again. This process continues, with reinforcement given for responses that are progressively closer to the goal and with prompts gradually faded as the subject learns.

Examples include teaching a rat to press a lever, teaching a child to speak a sentence, or shaping social behaviors in autism therapies under Applied Behavior Analysis. Key techniques include differential reinforcement, successive approximations, and prompt fading. Ethical oversight is important to ensure that reinforcement is appropriate and aligned with welfare and educational goals.

Shaping also exists in manufacturing and design. In metalworking, a shaping machine uses a fixed cutting tool that makes linear strokes to create flat surfaces, grooves, or slots. In crafts and sculpture, shaping refers more broadly to forming material through carving, molding, or forging.

Limitations include the potential for reinforcing unwanted steps if goals are not well defined, the risk of lengthy training, and the need for careful monitoring to avoid dependency on prompts. When used appropriately, shaping can enable the learning or creation of complex behaviors and forms that would be difficult to acquire in a single step.