Laurie's thumbsucking has become habitual because she begins to feel less anxious whenever she sucks her thumb. this best illustrates the process of:

This best illustrates the process of: operant conditioning

In operant conditioning, a certain behavior will be given a certain amount of reward or punishment in order to encourage or discourage them.
In this particular case, the thumbsucking is encouraged because she is rewarded by the feeling of less-anxious when she do it.

Im not but it is c