Implicationally Related Error Patterns and the Selection of Treatment Targets.

This paper compares some of the different claims that have been made concerning acquisition by traditional rule-based derivational theories and the more recent framework of optimality theory. Case studies of children with phonological delays are examined with special attention given to two seemingly independent error patterns, namely, place harmony and spirantization. Contrary to the expectations of derivational theories, these (and other) error patterns are argued to be implicationally related. Optimality theory is shown to offer a principled explanation for the facts with novel implications for clinical treatment.