Students of English as a foreign language (EFL) often have difficulty managing the complex nature of the formation of questions and negative sentences. The present study used a timed sentence correctness task to investigate the effects of word order and the presence or absence of clitic negation (i.e., don't, isn't, won't) on the processing of English negative questions by native speakers of Japanese. Two experiments were conducted, for both Yes/No questions and wh-questions. Each experiment included two correct conditions for the placement of negation, (a) (Why) Doesn't Mary drive? and (b) (Why) Does Mary not drive?, as well as two incorrect conditions, (c) (Why) Does not Mary drive? and (d) (Why) Does Mary drive not?. There were no significant differences attributable to student level, or between the correct and incorrect conditions. However, within the correct and incorrect groups there was a significant difference in the accuracy of responses. Students found it easier to decide the correctness of questions in the form (Why) Doesn't Mary drive? and (Why) Does Mary drive not? quickly and accurately. However, they had significantly more difficulty with questions of the form (Why) Does Mary not drive? and (Why) Does not Mary drive? Results suggest that there is little influence from LI Japanese syntax because students judged questions using the structure (Why) Does Mary drive not? which places not after the verb and is similar to the pattern for Japanese negation, to be incorrect relatively easily. The fact that the forms (Why) Does not Mary drive ? and (Why) Does Mary not drive? were not accurately judged as correct/incorrect indicates an overgeneralization of the equivalency of clitic negation, and non-clitic negation.

Key words: overgeneralization, clitic and non-clitic negation, Japanese EFL students