Game Development Reference
In-Depth Information
Visual
feedback
(incoherent/
haptic)
Visual
sensory
interface
Subject,
cognitive
level
Subject,
sensorimotor
level
Computer-
generated
images
Vision
Virtual
environment
Haptic
feedback
(incoherent/
vision)
Possible
command of
haptic feedback
Computer
processing of the
action and visual
feedback
Sensorimotor
haptic
interface
Coherent
perception
Incoherent
feedbacks
Touch
Initial
muscle
action
Motor action to
be processed
Mechanic processing of
motor action and
haptic feedback
Figure 2.8 Explanatory diagram of pseudo-haptic feedback
Though the discrepancies can cause discomfort and sometimes can also be unac-
ceptable, they can be cancelled out if the subject tries to find coherence with the world
and be a source of effective solutions as in the case of the phenomenon of vection.
It is with this same logic that we can use pseudo-haptic feedback. The principle of
pseudo-haptic feedback requires combining the visual feedback and the user's action
in the virtual world. This phenomenon, used in various virtual reality applications,
generates haptic sensations by modifying the visual feedback when the user acts in the
virtual environment, without necessarily requiring an active haptic feedback gener-
ated by simulation. The pseudo-haptic feedback thus corresponds to the perception of
a haptic property thanks to a new coherent representation of the environment. In the
explanatory diagram of pseudo-haptic feedback (Figure 2.8) given below, the subject is
stimulated by an incoherent set of visual stimuli and real haptic stimuli (as the latter are
not variable). The pseudo-haptic feedback would correspond to a reinterpretation of
these stimuli and an optimal visuo-haptic perception of a world which should remain
(or become) coherent to the subject.
The study of the sensorimotor discrepancies and the neurophysiological adaptation
to these discrepancies represents an open problem in the field of virtual reality, and is
one of the areas to explore for the researchers.
2.3.4 Interface and multimodality
Our interface analysis is simple: If the interface devices are generally different for each
sense at the sensorimotor level, at the cognitive level, the subject establishes coherence
in the perceived world and has a global and not a mono-sensory activity. One of
the biggest difficulties of interfacing is associating custom interfaces for each sense
and motor response 3 . How will the user coherently integrate the different sensory
stimuli that are generated by different artefacts? Currently, most of the systems using
virtual reality do not set up a multimodal interface, but rather opt for a multi-sensory
interface. This means using each modality independently. For example, the operator
will use his voice to give commands to the system (via a speech recognition module),
3 Except the force feedback interfaces which are sensorimotor and thus join a sense and a motor
response.
 
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