Answer:
The answer is shaping.
Step-by-step explanation:
In operant conditioning, shaping refers to rewarding similar behaviours to the target, until the objective is achieved. This is based on the concept of "successive approximations". For example, if a researcher is trying to teach a rat to pull a lever, he might reward other similar behaviours such as standing near the lever. Then, the rewards stop and another action (e.g. touching the lever) is reinforced. Eventually, the rat should be able to pull the lever.