This hypothesis was a theory first proposed by Dulay and Burt (1977) and it became known for agreeing with the ideas of a renowned linguist named Stephen Krashen, who contributed very much to the field of Applied Linguistics, mainly in the areas of acquisition and learning of second language. The main idea of this hypothesis is that there are affective filters that can directly interfere in the acquisition process of a second language. Such filters can bar or facilitate the action of an understandable input, so important to the acquisition process. Also, the action of these filters varies according to the attitudes of the acquirer, because their attitudes will determine the level of force that the affective filter will have, thus determining the effectiveness of an understandable input to the device of acquisition of the language. The main affective variations pointed out by Krashen are related to motivation, self-confidence, and anxiety. Therefore, any affective influence that falls into any of the three categories already mentioned may have a great effect on the development of language acquisition by the acquirer. It is therefore up to the acquirer, and not only to him, but to those who teach a second language, such as language school teachers, public or private school teachers, etc., to be aware of the importance of having the attitudes to provide the conditions necessary to diminish the action of the affective filter and thus the process of acquiring a second language to be well developed.
By M. B. Cavalcante
REFERENCE
KRASHEN, Stephen D. (1982). Principles and Practice in Second Language Acquisition (PDF). Oxford: Pergamon. Available in: <http://www.sdkrashen.com/content/books/principles_and_practice.pdf;. Access on Nov 24th, 2018.