8 1 Introduction: Divided Presence in Mixed Reality choice.In today’ssociety peopleoften choose to chat with text rather than speaking to someone else with their voice. This may be for economic reasons, or to reduce memoryload;butitmayalsobetoreducethesenseofpresenceinherentindealing with the communication. Waterworth and Waterworth (2006), give the example of one person waiting for a flight, who receives a text message from a loved one. She has plenty of time to compose a heartfelt reply, but starts her message with a playfully provocative remark.Assheisaboutto respondfurther,it is announcedthat her flight is actually at a different gate, quite some distance away. She will have to move quickly if she is to get to the gate on time, and so she has no time to finish the text exchange as intended, not even time to explain her current, changed situation. She sends the partially composed message anyway, because she was expected to do so, and runs to the newly announced gate. But the receiver, unaware of the context in which the messagewascomposed,completelymisunderstandsthesender’sintentandisupset byits tone and brevity. A communication medium with greater presence for both parties might have madetheproblemlesslikelytoarisealthough.Bydefinition,morepresenceevoked by a communication form means that more information about the present situation external to the sender is being transmitted. In a phone message, for example, the sender could explain the situation more quickly, while dashing to the correct location. And the sender would also receive indications of the sender’s true state, through paralinguistic cues such as breathing style, intonation, pitch and so on, as well as acoustic information from the surroundings. If video capability is also available, this tendency might be further enhanced, by showing facial expression, visual features of the surroundings, and so on. Contextual factors will affect a person’s state. One of the best ways of tracking contextis throughtracking a person’sstate, althoughwithout also tracking physical context this is open to misinterpretation. A person running to a departure gate at an airport needs primarily to attend to physical reality, but may yet be talking or texting a distant other person. This person may be sitting in an armchair, sipping a cupofcoffee,willingandabletobeimmersedinthecaller’scommunication.State- sensitivecommunicationdeviceswouldbeonewaytocaterforthefactthatdifferent individualswill often have the possibility for different levels of presence in different situations. People may also want to customise the level of concreteness – and hence potential for presence – of their communications according to the situation or the identity of the person they are communicating with. I may prefer to send a text than speak to a certain other person, and even if the situation makes it difficult to type, current technologyallows my speech to be presented as text if I so choose. Issues of communicational asymmetry described above point to a contextual reality gap between the parties, a gap that makes communication difficult when one, but not the other, is experiencing fragmented presence in a mixed reality. We discuss gaps in contextual reality, and our approach to dealing with them in detail, in Chap. 5. In the remainder of this chapter, we briefly summarise our approach and the scope of the rest of the book.