Training of Procedural Tasks Through the Use of Virtual Reality and Direct Aids - Virtual Reality and Environments - page 47

communication in a proper way, the multimodal sytems need high requiring hardware and
software technologies. Nowadays, due to the last advances in computer technologies to
increase their capabilities for processing and managing diverse information in parallel, the
multimodal systems are increasing their use.
Fig. 1. Multimodal system is a virtual system where the user interacts with the virtual scene
through more than one sensory modality.
According with Figure 1, a multimodal system can provide information to the user through
different types of interfaces, mainly:
1. Visual intefaces : the primary interaction style of the multimodal interfaces is usually the
visual interaction through computer display technology (such as, computer screens and
3D projections) to render the virtual scenario. In addition, these interfaces can be used to
provide relevant information for the task through messages, animations and visual aids.
2. Auditory interfaces : traditionally, sound in computer systems has been used either to convey
feedback to the users or alert them from a system event, for example, a beep to indicate
an error. However, some research studies are looking at the use of more complex speech
systems to provide richer non-visual information/interaction to the user. One example
of the research work in auditory interfaces is the auditory icons (Gaver (1994)) which
provide information about computer system events without the need to use any of the
visual display space.
3. Haptic interfaces : the word haptic comes from the greek haptikós and refers to the sense of
touch . The human touch system consists of various skin receptors, muscles and tendon
receptors, nerve fibers that transmit the touch signals to the touch centre of the brain, as
well as the control system for moving the body. In normal tactile exploration the receptors
in the hairless skin play the dominant role but in haptic interaction the focus is shifted
towards the proprioceptive and kinesthetic touch systems.There is usually a distinction
made between: tactile interfaces and force (kinesthetic) feedback interfaces. The tactile
interface is one that provides information more specifically for the skin receptors, and
thus does not necessarily require movement in the same way as a kinesthetic interface