This article comes to terms with the distinction made by Bühler between deixis ad oculos and deixis am phantasma. It is based on the study of conversations mediated by computers which are of very peculiar nature as the perceptive field is partially shared by the participants. Based on a study of the locatives in malagasy used in Instant Messaging, we argue that the complexity of the locative system in malagasy leads us to define the orientation of the interlocutors inside the perceptive frame they share.