The pre-scripted experiences can be focused on, letting you basically 'project' yourself into the story and experience like a dream, going through the story as if it were real. Afterwards, it feels like it was a particularly vivid dream.
Sierra can also project aspects of them out of the pearls onto herself or someone else, such as a specific form. Here she used one to project the Sao form onto herself, modifying taller it before doing so in the bottom sketch to mess with her little sister.