Question marker drop in Japanese and Generalized Factivity

Yoshida & Yoshida (1997) point out that the sentence-final particle no in Japanese questions can optionally be dropped, especially in colloquial speech. We refer to this phenomenon Q-drop in this paper.1 While Yoshida & Yoshida (1997) themselves almost never discuss interpretive effects of Q-drop, Sudo (2013) examines Q-drop in polar questions like (1) as cases of biased polar questions in Japanese. Sudo (2013) proposes that the two versions of this polar question differ in the so-called evidential bias they encode. We will defer our discussion of polar questions until the end, and for the bulk of the paper we will focus on interpretive effects of Q-drop in wh-questions like (1), which has scarcely been investigated previously (we are only aware of one relevant study, Miyagawa 2001, which we will discuss in Section 2).