Game Development Reference
In-Depth Information
Human senses
Philippe Fuchs, Moustapha Hafez, Mohamed Benali Koudja
and Jean-Paul Papin
We have already seen that a virtual reality device is designed and assessed on three
levels of Immersion and Interaction, the first level being the sensorimotor I 2 . The tech-
niques of virtual reality use behavioural interfaces (sensory and/or motor) to physically
join the computer with a human being. The design of such interfaces aims at creating
a hardware device that has efficient metrological characteristics that must, if possible,
correspond to the maximum capacities of senses and/or humanmotor responses. Under
these conditions, it is indispensable to have a clear and precise image of the human
sensorimotor behaviour in the real world to effectively analyse the behavioural inter-
faces as well as the sensorimotor I 2 . Hence we are going to discuss the characteristics
of specific sensory organs (vision, hearing, touch, smell and taste) and proprioceptive
organs that allow spatial location, balance, movements and displacements.
A human being perceives his environment through his senses. Reception of a sen-
sory stimulus is the starting point in the transfer of information in the body through
the nerve tracks. The afferent nerve message coming from the sensory receiver is trans-
ferred to the nerve centres (spinal cord, brain). After integrating and processing the
information, these centres transfer the efferent nerve message to the effector organs
(skeletal muscles, ocular muscles, muscles of the vocal cords, etc.). These organs per-
form the motor behaviour, which results in movements, except in case of the muscles
of the vocal cords that enable speech (Figure 3.1).
Every sensory impulse begins at specialised receptors. These receptors can be clas-
sified into two types. Some receptors, spread over our entire body, give information
about the state of the body and its overall senses (somesthesia). Other receptors, which
are specific to one sense, are located in the corresponding sensory organ. An example
is the photoreceptors of the retina for vision.
The exteroceptive receptors, which respond to external stimuli, inform us about
our environment. Proprioceptive receptors respond to the actions on the body: body
movements, its position in space and the forces exerted on the muscles.
We can make a general distinction between the two forms of stimulations -
imposed stimulation and obtained stimulation. An imposed stimulation comes from a
certain state of things which does not depend on the individual's own actions. A purely
imposed stimulation would take place when a completely passive and relaxed individ-
ual receives a sudden stimulation of light, sound, knock by an object, etc. On the other
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