The Audio-Lingual Method, like the Direct Method is also an oral-based approach. However, it is very different in that rather than emphasizing vocabulary acquisition through exposure to its use in situations, the Audio-Lingual Method drills students in the use of grammatical sentence patterns. It also, unlike the Direct Method, has a strong theoretical base in linguistics and psychology. Charles Fries (1945) of the University of Michigan led the way in applying principles from structural linguistics in developing the method. and for this reason, it has sometimes been referred to as the 'Michigan Method'. Later in its development, principles from behavior al psychology (Skinner 1957) were incorporated. It was thought that the way to acquire the sentence parterns of the target language was through conditioning- helping learners to respond correctly to stimuli through shaping and reinforcement. Learners could over come the habits of their native language and form the new habits required to be target language speakers.

LARSEN-FREEMAN, Diane. Techniques and Principles in Language Teaching. 3rd ed. Oxford ; New York: Oxford University Press, 2011.