Translated from the Portuguese original. Read the original (Português)
Shaping is how you teach a new behavior — one the person does not yet do — by reinforcing successive approximations: each step a little closer to the goal. Instead of waiting for the final behavior to appear ready-made (which might never happen), you reinforce whatever is already closest to it and, gradually, raise the requirement. That is how a baby goes from babbling to a first word, or how someone learns to swim, write, or play an instrument.
In Applied Behavior Analysis (Cooper, Heron & Heward), shaping is the differential reinforcement of successive approximations of a target behavior, until the person comes to display that behavior. It combines two processes: reinforcing responses that approximate the target and placing on extinction earlier approximations, which are no longer enough, as the criterion is gradually raised.
Why “shape”?
Some behaviors simply do not occur yet — so there is no way to reinforce them: reinforcement only strengthens what happens. If you waited for a child who has never spoken to say “water” perfectly before praising her, you could wait forever. Shaping solves this by starting from what already exists: the closest available approximation is reinforced, and once it is solid, a little more is required next time.
The name comes from a good image: a sculptor does not create the statue all at once — they give form to the clay bit by bit, adjustment after adjustment. In shaping, each reinforcement “shapes” the behavior one step at a time, in the direction of the target.
The staircase of successive approximations
Picture a staircase climbing up to the target behavior. Each step is an approximation that, once stable, gives access to the next step — always with reinforcement for “climbing”:
The two ingredients
Shaping is not “reinforcing just anything.” It is two processes working together. Tap the cards:
Shaping is not chainingShaping builds one new behavior, refining it step by step. Chaining is different: it links in sequence several behaviors the person already knows how to do (like the steps of brushing your teeth). Shaping forms; chaining connects.
Shaping what? The dimensions
You do not always shape the form of the behavior. You can approach the target along several different dimensions — sometimes more than one at a time. Explore:
Topography (the shape of the movement)
You shape the way something is done. Learning to write, a child goes from scribbles to strokes, then to rough letters, and finally to legible letters. Each version a little closer to the target letter is reinforced.
Duration (how long it lasts)
You reinforce staying on task for progressively longer periods. You start with 1 minute of focused attention, then 2, then 5 — raising the required time as the person advances.
Frequency (how many times)
You approach the target by the number of responses. In an exercise routine, you first reinforce 5 repetitions, then 8, then 12 — raising the goal little by little.
Intensity (how much force/amplitude)
You shape the magnitude of the response — speaking at an audible volume, gripping with enough force, stretching a little further each time. Approximations of increasing (or decreasing) intensity get reinforced along the way.
An everyday example: speech
Speech acquisition is the classic example of shaping that happens naturally, with no one planning it:
- the baby babbles random sounds — and adults respond with smiles and attention;
- gradually, sounds that resemble words (“ma-ma,” “wa-wa”) get more attention than generic babbling;
- the requirement rises: now only a clearer “mama” or “water” “works” to get what the child wants;
- until the clear word becomes solid — and the cycle starts over with new words.
The same principle shows up in therapy, at school, in sports, and in rehabilitation: whenever you teach something that is not yet in the repertoire, reinforcing approximations is the way. See also positive reinforcement, which is the engine behind every step.
Step size mattersSteps that are too big leave the person “stuck,” unable to reach the criterion — and the behavior can be lost for lack of reinforcement. Steps that are too small make the process slow and drawn-out. Finding the right step, and raising it only once the current one is solid, is what makes shaping work.
Where the concept comes fromShaping by successive approximations was described by B. F. Skinner in classic experiments (such as teaching an animal to perform a new action) and remains, to this day, a central, well-established procedure in Behavior Analysis for building new repertoires.
Test your understanding
Quick quiz
Three questions to reinforce the concept. You see the explanation right away.
Further reading
- Cooper, J. O.; Heron, T. E.; Heward, W. L. Applied Behavior Analysis. 3rd ed., 2020 — chapter on Shaping.
- Skinner, B. F. Science and Human Behavior. 1953.
- Catania, A. C. Aprendizagem: Comportamento, Linguagem e Cognição. 4th ed.
- Pryor, K. Don't Shoot the Dog: The New Art of Teaching and Training. Rev. ed., 1999.
This entry is educational and does not replace assessment, diagnosis or treatment by a qualified health professional. Every person is unique — for a specific case, seek individual guidance.