Development of a phobia
There are three theories about how people develop phobias:
In the biological theory, the phobia is represented in the brain as a biological entity. Some combination of different chemicals and hormones can affect a part of the brain when the person experiences anxiety.
Existential theory provides a model for generalized anxieties. These are disorders where there is no specific stimulus that causes the anxiety disorder. Central to this theory is that the subject becomes aware of a profound nothingness in his life.
The most commonly used theory is the behavioral theory [kaplan 91]. This theory is the most studied and used theory for treatments of phobias. Because it is the most studied and used theory, it also gives the best description of how to use the theory. This makes it easier for us to use it when treating people with Virtual Reality. The following sections will describe some of the most commonly used treatment schedules based on behavioral theory.
The other theories are also used to develop treatments, sometimes more than one method is used to develop a treatment [michelson 85] and [pollard 87].
Treatment based on behavioral theory
Behavioral theory has different groups of treatment. The following
sections will explain the following six treatments. Besides these
treatments, there are many more treatments developing and developed
[watkins 88] and
[michelson 84].
Systematic desensitization
Systematic desensitization consists of cycles of the following steps:
the subject has to relax. When he is relaxed, he has to imagine the
stimuli that causes a mild form of anxiety. Now he has to relax again
and when he is relaxed he is asked to stop imagining. These steps then
start all over again. Every time that the stimuli is not strong enough
anymore, he is asked to think of something more anxiety
producing. Belkin described this in the following order
[belkin 88]:
relax, imagine, relax, stop, imagine, relax, stop ...
Graded exposure
Graded exposure works almost the same as systematic desensitization,
but now there is no longer the relaxation part. Instead of having the
subject imagine the anxiety producing stimuli, he is now exposed to
the real anxiety producing stimuli, in vivo
[jansson 86],
[james 83].
For instance, a person afraid of spiders can be treated by having the
person watch a photo of a spider. When he is used to this, he can be
shown a spider from a distance. After this the subject can be taken
to the spider and eventually be asked to touch the spider. This
simple sequence can take several sessions to complete!
Flooding and implosion
With both these treatments, the subject is immediately exposed to the
highest level of anxiety producing stimuli. Unlike with graded
exposure and systematic desensitization, the subject is no longer
exposed step by step. This is like throwing someone in the swimming
pool and not having him step down a ladder. Implosion uses imaginal
stimuli and flooding uses in vivo.
Participant modelling
With participant modelling, the subject learns to overcome his anxiety
by following a fearless model. This can be the psychologist. When the
subject sees that the model has no problem exposing himself to the
stimuli, he might start to copy the models behavior. For instance,
when the subject is afraid of spiders and sees the psychologist touch
the spider, the subject might want to believe it is not as dangerous
as he thought.
Assertiveness and social skill training
Especially with social phobias, the subject has a lack of confidence
in himself. This can be trained with assertiveness and social skill
training. This teaches people how to respond in a social situation and
how to express their opinions in a normal way. Techniques used are:
role playing, desensitization, and positive reinforcement.
Aversion therapy / positive reinforcement
The final treatment described here is a form of behavior modification
through rewards or punishment. The punishment can be used to prevent a
subject from certain behavior. For instance, giving disulfiram to an
alcoholic will cause severe psychological consequences when
drinking. Positive reinforcement was used in a hospital ward where
mental patients could earn tokens as a reward for performing a desired
behavior. These tokens could then be used to buy privileges or luxury
items.
Choosing a treatment
The treatment used was chosen from the treatments described in the
section about behavioral therapy. Virtual Reality has the advantage
that the environment that the user sees can be controlled with high
precision. Using this higher control, it is hoped to get a better
understanding about presence, and to have a better treatment
available. Because of this reason, flooding and implosion are
discarded, since these treatments depend on showing the subject
immediately the highest level of anxiety inducing stimuli. To make
sure that it is the Virtual Reality that helps the subject and not the
relaxation, systematic desensitization is discarded. Aversion therapy
and positive reinforcement are discarded because they work with
physical rewards or punishments. Participant modelling is hard to do
in Virtual Reality because it requires two people to be present in the
same environment.
Using this knowledge, it was decided that the treatment given would be a form of graded exposure, but using computer generated images instead of imaginal or in vivo. The term used for this is going to be Virtual Reality Graded Exposure.
Development of environments
To give the user the feeling of height, it was decided to make models
of places that already give people a sensation of height. Different
scenarios that came up to be built were:
Once a month, the GVU center has an afternoon where the center is open to all visitors. People working in the GVU center demonstrate their work and answer questions. Using the people that come to these so called demo days, we tested the applications, and asked them what could be improved. Using this technique, we hoped to overcome some of the problems of prototyping [sol 92]: not enough validating of the application, and accepting the prototype too quick as a finished model. At the end of the summer, all the work that had been done during the summer had to be evaluated, to learn what caused the height sensations and to use this knowledge from the first environment to build the rest.
Since the hardest part of building applications for VR is creating the models and not building the software, it was decided to keep the prototype as an environment that could be used in the experiment. To prevent us from just building the software and the models without thinking first what they should look like, it was decided to build the first environment using the layered approach of Foley [foley 90]. This approach enabled us to get some idea about the application itself, before building it.
Finally, we needed to select one of the environments to be built as a first prototype. The application should also be used during the summer as a demonstration. To give the people coming over for a demo as much interaction as possible, we wanted to build an environment with which they could interact. This essentially eliminated all the environments except the elevator. The user should be allowed to control the elevator.
Requirements
This section will give some of the requirements put on the
environments. Some of the requirements were already given in the
previous section and some of them were given by the people in charge
of the project.
Rob Kooper |
kooper@cc.gatech.edu
|