What is presence?

The advantage of Virtual Reality is said to be the feeling of presence [zeltzer 92]. Already some research has been done as to what presence is, but none of this research has actually given a good definition of presence. This chapter will give a background on the research that has already been done to discover what presence is. The last section will explain what we hope to add to the knowledge about presence.

Previous work

Already some research has been done to understand presence. The following sections will describe what different people think about presence and what causes people to feel present in certain situations.

Most of the authors make a claim about presence and try to prove it using an experiment. Others will do an experiment and extrapolate rules about presence from it.

Thomas B. Sheridan

Thomas Sheridan works for the Department of Mechanical Engineering at MIT. He claims that there are three variables which are responsible for the feeling of presence [sheridan 92]:
Extent of sensory information has a much greater impact than the other two combined. These three factors however can not describe presence alone. Task variables, such as task difficulty and degree of automation, also are important to presence.

David Zeltzer

David Zeltzer works for the Computer Graphics and Animation Group at the Media Laboratory, MIT. Presence is, according to Zeltzer, the number and fidelity of available sensory input and output channels. According to him, a discussion about presence is meaningless without specifying the application domain and task requirements [zeltzer 92]. He also claims that it is not possible to simulate the physical world in all its detail and components. There should be research done to identify the different sensory cues that must be provided to complete a task.

Alaric Naiman

In his article, Naiman discusses what reality is [naiman 92]. According to him reality is that what the person perceives it to be. In other words, each of us creates his own reality. To be able to do this, our minds can produce or remove cognitive distortions.

Carrie Heeter

Carrie Heeter works for Michigan State University. According to Heeter, there are three dimensions of presence [heeter 92]:

Subjective personal presence is based on simulating real world perceptions. You feel that you are there because everything responds as in the normal world. Social presence is stimulated by the fact that other people or beings are in the virtual world. With environmental presence it is meant that the modeled environment is aware of the user, i.e. doors open in front of the user.

Richard M. Held and Nathaniel I. Durlach

Richard Held and Nathaniel Durlach work at the Department of Brain and Cognitive Science and the Department of Electrical Engineering and Computer Science, MIT. In their article, the authors write about telepresence [held 92]. They claim that telepresence will increase when the operator can identify his own body with the slave robot. This can be achieved by a high correlation between the movements of the operator, sensed by the operator via internal kinesthetic senses, and the actions of the slave robot, sensed via the sensors of the robot. Sensory factors that improve telepresence are a high resolution display and a large field of view.

Gary Fontaine

Gary Fontaine works for the Department of Communication at the University of Hawaii. Fontaine has done research to find out about presence in an intercultural and international encounter [fontaine 92]. He did research to find how much presence people felt in a new environment, a new culture. He did this by asking the people whether or not they felt present in their new environment. He found that people who are in a new situation, a new virtual environment, have a high degree of presence. This high level of presence lessens over time.

Gerda J.F. Smets et al

In their article [smets 94], the authors describe a design package developed at the faculty of Industrial Design at the Delft University of Technology. This design package is built using the ecological approach to perception as described by Gibson. Ecological refers to the importance of the relationship between the subject and the environment. For instance, the texture of the ground becomes less visible the further we look. Using this we can measure distance. Another clue we use to measure height and distance is the height of well known objects, for instance a building, a car or a bicycle.

Lessons learned from previous work

The level of presence felt in Virtual Reality is dependent on many different factors. Previous work has shown the following factors play a role in the level of presence:
The person creating Virtual Worlds should also have knowledge about the application domain and the task that has to be performed.

Questions

The previous sections described some of the work that has been done to understand what presence is. After reading and discussing the work in the Virtual Environments group and with my advisor, we came up with the following five questions. We think that answering these questions will help to understand what presence is.
  1. Is there a definition of presence that is sufficiently operational and quantitative to be useful?
  2. What are the factors that create a sense of presence?
  3. Are there subjective and objective measures that can quantify presence?
  4. Are there applications for which a sense of presence actually improves operator performance?
  5. Are there applications for which presence is a necessary ingredient? If so, how are these applications different from applications for which a more traditional display system is just as effective?
The last two questions are especially important for Virtual Reality. These questions give Virtual Reality a basis to build on. If there are applications for which presence is a necessary ingredient and the level of presence can only be achieved using Virtual Reality, then that is a justification to continue doing research in Virtual Reality.

Conclusions

To get to know more about presence and especially the level of presence we can achieve using Virtual Reality, we need to find an application in which presence is a necessary ingredient. From previous work, five questions have been extracted about presence. These five questions described in the previous section are sub-questions of the following research question:
Identify and explore issues related to the Virtual Reality concept usually referred to as presence.

To answer this questions and the five subquestions, an application is needed where presence is a necessary ingredient. At the same time that we were talking about what kind of application would help to explore presence in Virtual Reality, we were also talking to psychologists about a joint effort in Virtual Reality. The psychologists launched the idea to use Virtual Reality to treat people suffering from phobias. This would give us an application where it is absolutely necessary for the subject to feel present and would give the psychologists the possibility to test whether it was possible to use Virtual Reality in psychology. This raised the following research question:
Examine the efficiency of a treatment for a phobia by using Virtual Reality.

The next chapter will look at different forms of phobias and how they can be treated. The different phobias were compared and a single phobia was selected. The same was done with the treatments. A single treatment was selected to be used with the phobia.


Virtual Reality Choosing a phobia TOC
Rob Kooper
kooper@cc.gatech.edu

Last modified: Wed Aug 9 12:14:03 GMT 1995