Difficulty and Complexity of Language Features and Second Language Instruction

The question whether some second language (L2) features (forms, items, structures, patterns, rules) and, if so, which types of features, are more affected by instruction or are more effectively instructed than others has received increasing attention in applied linguistics and SLA research since the mid-1990s (VanPatten, 1994; Spada, 1997). For SLA researchers, knowing how the nature of the input stimulus interacts with the human cognitive processing and learning mechanisms is important for constructing a comprehensive theory of language acquisition. For theoretical, typological and psycho-linguists, knowing which types of features of language are hard to learn and teach can inform theories of language and processing complexity (Szmrecsanyi & Kortmann, 2012). For L2 teachers and curriculum and textbook developers, knowing which type of L2 features to select in the typically limited teaching time is important for optimizing L2 teaching and learning effectiveness (Doughty & Williams, 1998).