Game Development Reference
In-Depth Information
be more difficult, and learning will take a longer time because it will be less similar
to the real. If using an IBS instead of using a metaphor with or without substitution
in turn means using technically imperfect interfaces, the action will be difficult. This
might further obstruct the user's action, even if it is closer to a similar action in the
real world.
Another criterion is important to study in order to know whether to use an
Imported Behavioural Schema. In the case where the sensorimotor action itself is a
subject of study, which is often the case while designing a product, the use of an IBS in
the virtual world is indispensable and must be physically as close to the schema as in the
real environment: for example, operating the command buttons of an instrument panel
for the study of this product. On the other hand, if the sensorimotor action is used
only to indicate what the subject wants, using an IBS is not indispensable and should
be compared to using a metaphor with or without sensory or motor substitution. It is
thus necessary to analyse the application to know whether it is an activity studied at
the sensorimotor level (schema is indispensable) or a mere indication of activity. We
will discuss this further in the next paragraphs.
Even though the examples mentioned above have been given to differentiate
the choice between an IBS and a metaphor with or without substitution, there are
some applications where the choice between different cases is not exclusive. We can
consider that there is a certain continuum of solutions between the extreme cases
(only IBS or pure metaphor) for the cognitive processes of interaction and immer-
sion. Use of Imported Behavioural Schemas or metaphors, with or without sensory or
motor substitution, is the topic of a never-ending debate in the scientific community
(Fuchs, 1999).
2.3.3 Consistency and discrepancy of virtual
environment
As we mentioned earlier, the techniques of virtual reality almost always induce
discrepancies, either within one sense (for example, discrepancy between accommo-
dation and convergence of the eyes in a stereoscopic vision) or between multiple
senses (for example, the locomotion on a moving walkway that causes discrepancy
between vision and kinaesthesia), or between sense and motor response (for exam-
ple, handling virtual objects without force feedback). In the real world, man builds a
coherent representation on the basis of all the sensory stimuli received. In the virtual
world, the user will thus try to interpret whatever he perceives coherently, in spite of
the sensorimotor discrepancies between the virtual world and his experience in the
real world.
However, it is currently very difficult to determine offhand whether the subject,
immersed in such or such virtual environment, will be able to perceive these coherent
environments and overcome the sensorimotor discrepancies. Based on some cases in
the past, we can state that the person can overcome certain discrepancies. In front of a
big screen showing images of a world in motion, he feels that even he is moving. It is the
vection phenomenon that creates the sensation of movement, even though the person
does not detect any movement through his vestibular system. But if the movement is
too fast, or rotary, discrepancy cannot be overcome, and creates discomfort for the
subject, like the well-known discomfort of simulators.
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