Reinforcement: Learn It 1—Shaping

  • Define shaping
  • Understand the difference between primary and secondary reinforcers
  • Distinguish between interval reinforcement schedules
  • Distinguish between ratio reinforcement schedules

Shaping

In his operant conditioning experiments, Skinner often used an approach called shaping.

shaping

Shaping is the process of rewarding successive approximations of a target behavior.

Reinforcement works only if the organism already performs some version of the behavior. But many behaviors—writing an essay, playing a sport, or training an animal—don’t appear all at once. Shaping breaks the behavior down into manageable steps, and each step is reinforced as the learner gets closer to the final goal.

How Shaping Works

Skinner outlined a clear sequence:

  1. Reinforce any behavior that resembles the target behavior.
  2. Reinforce behaviors that more closely resemble the target behavior; stop reinforcing earlier steps.
  3. Continue to reinforce increasingly accurate approximations.
  4. Reinforce only the final, desired behavior once it reliably appears.

Skinner used shaping to teach pigeons not only such relatively simple behaviors as pecking a disk in a Skinner box, but also many unusual and entertaining behaviors, such as turning in circles, walking in figure eights, and even playing ping pong; the technique is commonly used by animal trainers today. 

Shaping is often used in teaching a complex behavior or chain of behaviors. Here is a brief video of Skinner’s pigeons playing ping pong.
You can view the transcript for “BF Skinner Foundation – Pigeon Ping Pong Clip” here (opens in new window).

Examples of Shaping

Children cleaning their room:

  • Step 1: Pick up one toy → reinforcement
  • Step 2: Pick up five toys → reinforcement
  • Step 3: Choose between putting away books or clothes → reinforcement
  • Step 4: Clean everything except two toys → reinforcement
  • Step 5: Clean the entire room → reinforcement

College-life example:

A student procrastinates writing a 10-page paper. A shaping plan might reinforce:

  • Opening the document
  • Writing the first paragraph
  • Writing one page
  • Completing the full draft
  • Submitting the final paper

Shaping often works hand-in-hand with stimulus discrimination, helping learners respond to the correct cue (e.g., responding to a trainer’s whistle but not similar sounds).