Answer:
Classical conditioning
Step-by-step explanation:
There are three main types of conditioning: classical, operant and observational.
In a classical conditioning, people associate events and stimuli that frequently happen together and they learn to anticipate these events. The most famous example of classical conditioning is Ivan Pavlov's experiment with his dog.
Elaine's baby is still sucking on the nipple even if the bottle is empty because he/she associates the bottle with feeding and the mother's presence.