To what extent does the quality of input affect the process and ultimate attainment in second language acquisition‪?‬

This essay addresses a question which is central to input research, namely to what extent the quality of input has an effect on SLA, particularly on the learner's ability to comprehend. Thereby the term 'quality' shall be interpreted as referring to any impact of modified input and negotiated interaction that is not related to its amount or frequency. After a brief review of Krashen's Input Hypothesis, Long's Interaction Hypothesis and Swain’s Comprehensible Output Hypothesis, I will then proceed to suggest ways in which Foreigner Discourse modifications might facilitate SLA. I shall also review a number of studies dealing with (un)modified input-SLA relationships, among which are Long’s (1985) and Gass & Varonis' (1994) study. Due to the constraints imposed upon this essay, I will of course be drawing upon a very small selection of the pertinent literature.