In shaping a sign, which sequence represents the order of successive approximations described for teaching the sign 'please'?

• A. First reinforcing lifting the hand, then reinforcing lifting the hand to the chest, then reinforcing lifting the hand to the chest and moving it slightly, and finally reinforcing lifting the hand to the chest and moving it in a circular motion.
• B. Reinforcing random hand movements until the sign is produced.
• C. Reinforcing only after the full sign is performed with no partial movements.
• D. Punishing any partial attempt and withholding reinforcement.

Answer: (A)

Shaping a sign relies on reinforcing closer and closer approximations to the target gesture, so the learner builds the exact movement step by step rather than all at once. The sequence shown starts with a simple movement that resembles the sign—lifting the hand—and each subsequent step adds a feature that brings the topography closer to the desired sign, with reinforcement at each stage. Next, bringing the hand to the chest is rewarded, then adding a slight movement at the chest, and finally reinforcing the full, circular motion of the sign. This gradual progression helps the learner acquire the precise motor pattern through successive approximations and differential reinforcement.

Reinforcing random hand movements wouldn’t guide the learner toward the specific sign, reinforcement only after the full sign offers no practice for incremental improvement, and punishing partial attempts would suppress attempts and undermine the shaping process.