This article explores the issue of the psychological reality of null expletives,
i.e., the silent counterparts of the so-called dummy subjects such as English
it and there. Following Jackendoff’s (1997; 2002) notion
of `defective’ lexical item, I define null expletives as extremely
`defective’ words with syntactic properties but no semantic or
phonological content. By comparing native speakers of pro-drop languages
and those of topic-drop languages in terms of their grammatical judgement
of and productive use of English, I argue that null expletives are very likely
psychologically real to speakers of pro-drop languages but not to those of
topic-drop languages. This conclusion is based on observations made in
previous second language (L2) studies and the analysis of data obtained from a large
corpus of nonnative English. The question of the unaccusative-unergative distinction
in L2 grammar and the linguistic characterization of so-called free subject-verb
inversion in pro-drop languages are also discussed in relation to the issue
of the psychological reality of null expletives.