The term “telepresence” was coined by Marvin Minsky in 1980 and refers to the phenomenon that a human operator develops a sense of being physically present at a remote location through interaction with the system’s human interface [1]: through the user’s actions and the subsequent perceptual feedback he/she receives via the appropriate teleoperation.

Teleoperations are a specific type of VR that allow the individual to operate in a distant environment (e.g., in space, in the depths of the sea or harmful locations). The user is given the opportunity to command a machine with an anthropomorphic design, which moves according to the user’s movements and gives both auditory and visual feedback [5].

Such sensory feedback is of sufficient quality and quantity to maintain the operator’s feeling of presence in the remote workplace [6]. The operator perceives two separate environments simultaneously: the physical environment where he or she actually is, and the environment, which is being presented via the technology. The term “telepresence” is used when the virtual experience dominates the real world experience. So it describes the feeling of being in the environment generated by the technology, rather than the surrounding physical environment [4].

However, the term “presence” entered in the wide scientific debate in 1992 when Sheridan and Furness used it in the title of a new journal dedicated to the study of virtual reality systems and teleoperations: Presence, Teleoperators and Virtual Environments. In the first issue, Sheridan [3] refers to presence elicited by a virtual environment as “virtual presence”, whereas he uses “telepresence”only for the cases involving teleoperations [4].

Nowadays, most new VR devices are not used to operate at a distance. Rather, these systems generate a virtual environment in which the user can participate: not by altering an external real world, but by altering a virtual world generated by the computer. The participant ceases to think of himself as interacting with a computer and starts to interact directly with the three dimensional environment.

The Two Sides of the Same Coin: Media Presence and Inner Presence

An electronic Forum “Presence-L Listserv” established in July 1999 by the Information Systems Division of the International Communication Association, hosted a discussion of presence in 2000. A tentative definition of the concept of presence resulted from this:

“Presence is a psychological state or a subjective perception in which the participant, although working with an instrument, fails to understand the role of technology in his experience. Although the subject might assert (except in extreme cases) that he is using technology, up to a certain point, or a certain degree, the subject gets involved in the task, in objects, entities and event perception, as if technology was not present” [7].

Although quite comprehensive, this is not the last word on the debate of the term’s meaning. Presence entails some emotional involvement and is related to different levels of realism [8].

Many different definitions and descriptions of media presence exist, although it is almost always defined as a feeling of being present in a virtual environment [9]. The objective for most researchers is to develop an operational definition of media presence, with objective measures that may determine adequate levels of presence for the accomplishment of certain tasks. Bearing in mind these aspects, a definition of presence would allow standardization of its evaluation as a valid and reliable measure.

The VR generating systems comprise two main parts: a technological component and a psychological experience. Following this, there will be a dichotomy of the definitions and explanations of the feeling of presence: the rationalist and the psychological point of view.

The rationalist point of view considers a VR system as a collection of specific machines with the necessity of the inclusion of the concept of presence. The researchers agreeing with this approach describe the sense of presence as a function of our experience of a given medium (Media Presence). The main result of this approach is the definition of presence as the perceptual illusion of non-mediation produced by means of the disappearance of the medium from the conscious attention of the subject.

However, the technologic definitions of VR do not deny existence of the psychological component offered by the VR systems, it is simply not included in the definition. At the other extreme there is the psychological or ecological perspective (Inner Presence).

As discussed in the recent two chapters by Riva and by Waterworth et al., in the book "From Communication to Presence", the feeling of presence is seen as an experience common among different types of human experiences independent of any technology. Specifically, these researchers consider presence as a neuropsychological phenomenon, evolved from the interplay of our biological and cultural inheritance, whose goal is the control of the human activity [10-11].

The logical extension of this definition, as discussed by Moller and Barbera, is that dreams too are virtual experiences involving presence.

The rationale behind the concepts of Media Presence and Inner Presence is discussed in the next pages.