Hull's theory is supposed to be a general theory on which learning is grounded. A bigger percentage of research on theory were conducted where animals were used as the sample except for Hull et al. (1940) which focused on verbal learning (Miller & Dollard 1941).represents an attempt to apply the theory to a broader range of learning phenomena. As an interesting aside, Hull began his career researching hypnosis - an area that landed him in some controversy at Yale (Hull, 1933).
Here is an example described by Miller & Dollard (1941): A six year old girl who is hungry and wants candy is told that there is candy hidden under one of the books in a bookcase. The girl begins to pull out books in a random manner until she finally finds the correct book (210 seconds). She is sent out of the room and a new piece of candy is hidden under the same book. In her next search, she is much more directed and finds the candy in 86 seconds. By the ninth repetition of this experiment, the girl finds the candy immediately (2 seconds). The girl showed drive she had for the candy and searching for it in books is .After finding the correct book a reward was forwarded leading to a habit.