Second language data and constraints on Manner: explaining substitutions for the English interdentals
Substitutions for English interdentals tend to be consistent based on first language (L1): eg. [t] for speakers of Russian, [s] for speakers of Japanese. While the facts suggest that some type of L1 transfer must be involved, a rule affecting a sound that does not occur in L1 is unlearnable. Optimality Theory (OT) allows a solution to this conundrum because the grammars contain independently necessary constraint rankings that also have an effect on the interdentals. [t] substitution results from high ranked markedness. This can be seen as an effect of universals because this grammar retains the original ranking that the L1 learners begins with. [s] substitution results from high ranked Faithfulness. In this case, some L1 phonology has forced reranking, making this an effect of L1 transfer.