Multi-Sensory Feedback (5) - By Yasmin Aftab

Multi-sensory feedback technology is widely adopted in virtual reality environments. In order to evaluate its usability proper tests should be performed. In the study of Zhang et. al. (2007) an assessment of multi-sensory feedback on the usability of a Virtual Assembly Environment was conducted. VAE in the manufacturing industry, allows easy evaluation of assembly-related engineering decisions through analysis, predictive models, visualisation and data presentation. In addition, it has the potential to factor the human elements and considerations of the completed product without needing a physical realisation. For the non-command interface an optical tracking system was applied which provides a real time measurement of the position and orientation of the tracked targets i.e. user’s head and hands.

The experiment assessed 3 different attributes of the system: efficiency of use, user satisfaction and reliability. In order to evaluate the attributes task completion times, questionnaires and human performance error rates were used respectively. A group of 16 people was invited to conduct the tests. The research assumed several hypotheses:

• The use of visual feedback can lead to better usability than neutral condition (neither visual nor auditory feedback)
• The use of 3D auditory feedback can lead to better usability than the neutral condition
• The use of integrated feedback (both visual and auditory) cal lead to better usability than either feedback used in isolation

The results of the experiment show that the use of multi-sensory feedback(integrated) improves the efficiency of use (as the tasks were completed much faster), user satisfaction (more participants prefer the integrated feedback and it is more helpful) and reliability (mistakes, slips, lapses and mode errors happen less frequently with the integrated feedback).

Apart from the evaluation of the usability, the multi-sensory feedback still has some design issues that need to be overcome. The design issues of spatial input (Hinckley et. al.) might be grouped in two categories: human perception and ergonomics and facility of interaction. Multi-sensory feedback is essential to the understanding of space (Gibson). However, some of the appliances used in a virtual reality interface may not provide appropriate feedback for the user. According to the experiment (Hinckley et. al.) with a virtual flashlight, the glove-based input might be helpful but there are some kinematics constraints of a hand that does not allow certain movements.

For example: it is easier to rotate something held in fingers that to rotate the whole hand itself. Additionally, the mass of a tool is quite important as it can damp instabilities in the user’s hand motion which is very important i.e. for the surgeons. As far as ergonomics is concerned, several problems may occur. In case of complex applications such as document editor, direct manipulation needs to be constrained by techniques like girding. Appropriate feedback mechanisms still need to be developed for use in spatial interfaces.

In short hand, “The design hurdle is this: provide an interface which effectively integrates rapid, imprecise, multiple degree-of-freedom object placement with slower, but more precise object placement, while providing feedback that makes it all comprehensible. In a nutshell, the usability evaluation of multi-sensory feedback technology is possible after the product is launched. It is done by the people who will buy or use the product. Because of the financial reasons it might be a risky venture, but it is essential for the development of pervasive computing. In most cases, applied multi-sensory feedback technologies are successful and helpful in our life. The last example presents how people’s sensory processing disorder can be overcome with the use of new technologies.
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References:
Evaluation of Multi-sensory Feedback on the Usability of a Virtual Assembly Environment [online] available from http:// www.academypublisher.com/jmm/vol02/no01/jmm02013847.pdf [February 2007]
2. Hinckley, K. , Pausch, R. , Goble, J. C. , Kassell, N. F. (1994) Proc. ACM UIST'94 Symposium on User Interface Software & Technology [online] available from http://www.cs.cmu.edu/~stage3/publications/94/conferences/UIST/Survey.html [April 1994]3. Gibson, J., The Ecological Approach to Visual Perception. Lawrence Erlbaum, Hillsdale, NJ.