Morphological uniformity and the null subject parameter in adult SLA

Abstract

An area of keen interest in applying Chomsky's UG parameter-setting model to SLA has been the Pro-Drop or Null Subject Parameter (Cyrino, 1986; Hilles, 1986; Phinney, 1987; White, 1985, 1986). However, the nature of this parameter changes dramatically from the Jaeggli (1982) and Rizzi (1982) conception with Jaeggli and Safir's (1989) proposal linking uniform morphological agreement paradigms with null subjects. Data reported here show a number of L2 learners exhibit knowledge that English is morphologically nonuniform yet still accept English null subject sentences. This is inconsistent with the predictions of the Morphological Uniformity Hypothesis and renders uncertain its applicability to SLA. The results are considered in light of a number of possible positions that can be adopted when faced with data that disconfirm a hypothesis within the UG SLA research program; it is concluded that the Morphological Uniformity Hypothesis is disconfirmed and that any reformulation of the Null Subject Parameter must take these results into consideration.