The present paper analyses speech level shifts in Japanese from a different perspective. By applying Symbolic InteractionistRole Theory, speech level shifts are categorised as the linguistic realisation of aninteractional role, or ‘dissociative role’ Icall in this paper. Dissociative roles are improvised identities, which occur when the speaker perceives a psychological change in relation to the other participant in the on-going interaction. Plus-level shifts (shifts from plain to polite forms,masu/desu) are triggered when the speaker experiences cautious, attentive, thoughtful and/or grateful feelings at a certaintime of interaction, which conforms to the original nature of honorifics. This prompts a dissociative role which creates a certain psychological distance between this role and the other interactant. On the other hand, minus-level shifts (shifts frommasu/desuforms to plain forms) are the implementation of the speaker’s another dissociative role, which is assimilated with the other interactant, giving rise to empathy or drawing the other into the speaker’s world. Whether plus or minus level shifts occur, the interactants’social roles, i.e.,their original roles when the situation is defined, continue to exist throughout the discourse. The interactants are fully aware of their social roles such as teacher and student, friends, family members, and senior and junior in company(= Institutional Roles in this paper). However, when an Improvised Role is created, it is forwarded to the on-going interaction and linguistically implemented as a speech level shift.This paper also clarifies that both speech level shifts and the so-called ‘conventional’honorifics are situationally determined, and that they are not separate entities but the two ends of continuum by examining the features they share from the viewpoint of ‘roles’.