This is best explained through the process called classical conditioning.
Explanation:
Classical conditioning is a learning process that involves an association between a stimulus and a response. In the example given in the question, the stimulus is the bottle, which was an indication that she would soon be fed, and it was paired with the excitement that she felt when eating (unconditioned response). Therefore, after the association is been made, the conditioned stimulus (the bottle), produces the now conditioned response (the excitment).
When a person is being paranoid, he or she can not stop thinking of negative happenings or thoughts that may happen to him or her. These type of persons are suffering from the mental condition commonly known as paranoia
