Another way to make this same objection is to focus somewhat differently on the concrete material difficulties involved in creating successful—that is, compelling—virtual environments. As Wann and Rushton point out, the limitless potential of the imagination to construct rich virtual environments is contravened by the reality of storage and computational limitations. The Gibson-inspired researchers believe they can “solve" these difficulties through texture-gradient mapping; by building in “objective" elements that simply transcribe perceptually invariant elements of the “real" world into VEs, they think they can mobilize, through visual stimulation alone, the perceptual modalities for which we have been evolutionarily hardwired.viii
In their interpretation of the storage and computational limitations necessarily encountered in designing VEs, Wann and Rushton outline a very different position. For them, the existence of such limitations immediately introduces a wedge or gap between “real-world" perception and perception in virtual environments that bears directly on the misapplication of Gibson just discussed. For these researchers, the presupposition that perception (including visual perception) involves the full panoply of perceptual systems—the presupposition informing Gibson's theory—simply cannot be carried over to perception in VEs. As a consequence, whereas perception in “natural settings” can be said to be “veridical" (i.e., indicative of properties of the environment), the principle informing the creation of virtual environments is, of necessity deception." Wann and Rushton explain:
It is technically impossible to present an observer with a VE that has coherence across the perceptual domains (e.g., for vision and vestibular stimulation) ... [Consequently,] the emphasis has to be on presenting visual displays that are salient enough to induce the required percept and to establish what other sensory conditions may be necessary to maintain that illusion.10
What Wann and Rushton foreground here is the necessity, in creating compelling VEs, to rely on the embodied subject's response to the stimuli presented as what generates the effect of "reality." Some degree of corroboration among different sensory registers is always involved in perception; however, within VEs, this corroboration plays an especially important function insofar as it constitutes the primary vehicle for overcoming effects of storage and computational limitations— effects that threaten to compromise the desired sense of immersion.
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