The Threshold for Haptic Engagement
At one extreme, the body requires a sum of stimuli and information that far exceeds that of the visual regime. In order to properly calibrate the simulation to the expectations of total haptic engagement, an all-encompassing virtual reality technology would seem to necessitate a cumbersome apparatus capable of simulating not only the experience of the body in space, but also its interaction with a wealth of stimuli (ambient temperature, wind, the solidity of an object, etc.) by means of elaborate networks of force feedback and magnetic manipulation (207). Nothing as of yet can “reproduce a real and complete tactile/haptic interaction with an object,” the comprehensive transmittance of proprioceptive signals, the weight and surface properties of the object, and so on (207-8).
The skin, then, presents very real problems for sensory immersion, hence the inability to simulate the process by which “tactile sensations continuously arise from all parts of our body” (209). Yet this apparent technical shortfall is belied on multiple fronts. As Gallace and Spence note: Scientific research has shown that: (1) Tactile receptive fields are larger on certain areas of the body (e.g. the back) than others…Consequently, a smaller number of stimulators can be used on those parts of the body… (2) People do not appear to be aware that multiple stimuli are being presented on their skin…whenever more than three stimuli are presented at the same time. (211)
It is therefore possible to manipulate the body selectively as a means of advancing a haptic simulation. What’s more, it is only truly necessary to “render a small percentage of the available information (for example, that concerning stimulus transients) in high definition in order to elicit a given precept” (212). Thus, what is constant does not need to be modified and, as has been proven in regard to vision, selective, high definition stimulation can suggest a comprehensive approach by exploiting the brain’s inability to process information outside of a spectrum rendered in terms of volume, density, and richness.