INTRODUCTION It is a widely accepted fact that in order to learn a language, one must receive the necessary data. This data is the language that the learner is exposed to through any medium such as listening, reading, or gestures in the case of sign languages (Gass & Mackey, 2006, 2007). In acquiring their first language, children receive a large quantity of L1 data from their parents and the surrounding environment. In learning a foreign language, the majority of the learners receive the L2 data from language classes. This data is provided to them through two main sources of input: the teacher and the textbook. A long-held debate among applied linguists as well as practicing teachers has been concerned with what kind of input is optimal for learning a foreign language. Should learners be exposed to authentic materials or simplified ones? If simplification works, how should it be brought about? These are the controversial issues that are still unresolved. While a number of studies have shown that modified input facilitates comprehension (Oh, 2001; Yano, Long & Ross, 1994), there is still ongoing debate as to what kind of modification is desirable. There are two important positions which ought to be examined in this respect. The first is Krashen's Input Hypothesis (1981, 1982, 1985), which maintains that comprehension is facilitated through simplification of input, and the other is Long's interaction hypothesis (1983, 1985), which argues for superiority of interactional modifications to simplification of input.
