Acquisition – used interchangeably with learning but as hypothesized by S. Krashen, a different mental process. Acquisition is an unconscious process driven by the brain’s language Acquisition Device, a hypothesis of Chomsky. When presented with communication, the brain automatically processes it for information in the form of meaning. Features of the language (L1 or L2,3,4…) will be registered in the brain as the learner recognizes patterns. These patterns build an interanl model of the language which the learner can then draw on for production.
Opponents of acquisition theoryderide it with the term ’osmosis’, basing their theories of SLA on cognitive psychology, where conscious knowledge of rules leads to acquisition through practice. Those who see knowledge of language as unconsciously acquired often refer to such knowledge as intuitive knowledge.
A problem for the proponents of acquisition theory is how to distinguish it from what Krashen calls ’learning’, or conscious knowledge about language. Krashen maintains that such conscious knowledge cannot be transferred to the acquired realm; that only happens through the unconscious process.
A problem for the opponents of acquisition theory is explaining how mankind has learned other languages throughout the ages with no grammar books, no schools or classrooms, no organized, written set of rules, and so forth.