This study provides a cognitive stylistic analysis of one of the most poignant parallel worlds created in contemporary mental illness memoirs- Susanna Kaysen's Girl, Interrupted. More specifically, this study involves a Text World Theory perspective on Kaysen's Girl, interrupted to explore the reader's cognitive interactions with the text through the analysis of the stylistic particularities of psychologically loaded episodes in terms of the shifting between matrix textworlds and the generated subworlds. This research also draws upon the "Split-self" phenomenon and the notion of "Mind-style" to highlight the way textual features and narratorial techniques cue the reader's navigation between various alternative worlds and conceptual points of view and to elucidate the blurred narrative consciousness employed in this memoir. This was demonstrated through textual analysis which suggested that being exposed to parallel worlds inhabited by alter selves is, in part, what allows the reader to experience the different aspects of the story from particular points of view filtered through idiosyncratic mind-styles