ABSTRACT
This chapter describes and illustrates a variety of procedures for reducing or eliminating the deleterious effects of the sensory rearrangements that plague virtual environment (VE) technology. A sensory rearrangement exists when the sensory array and/or the relationship between sensory systems differs from normal. A well-known example is viewing one’s hand through a light-displacing wedge prism (e.g., Redding & Wallace, 1997). Initial exposure to a sensory rearrangement causes misperception, the surprise of violated expectations, and sensory-motor disruption. Due to limitations in many current VEs, users are often exposed to such rearrangements, with predictable consequences for perception and behavior. For example, a mismatch between a hand tracker and the visual image of the user’s hand can be expected to produce the same kind of sensory rearrangement as prismatic displacement. Because human beings can adapt to a wide range of sensory
25.1 Overview ............................................................................................................................. 627 25.2 Adaptation as a Solution to VE Limitations ....................................................................... 628 25.3 Sensory Rearrangements Found in Some VEs ................................................................... 629
25.3.1 Intersensory Conªicts ........................................................................................... 630 25.3.2 Depth and Distance Distortions ............................................................................ 631 25.3.3 Shape and Size Distortions ................................................................................... 632 25.3.4 Delays of Sensory Feedback ................................................................................. 632 25.3.5 Sensory Disarrangement ...................................................................................... 633
25.4 Adapting to Sensory Rearrangements and Applicability to VE Training Procedures ....... 634 25.4.1 Stable Rearrangement ........................................................................................... 634 25.4.2 Active Interaction ................................................................................................. 635 25.4.3 Error-Corrective Feedback ................................................................................... 636 25.4.4 Immediate Sensory Feedback ............................................................................... 636 25.4.5 Incremental Exposure ........................................................................................... 637 25.4.6 Distributed Practice .............................................................................................. 638
25.5 Optimal Adaptation-Training Procedure and How to Counteract the Drawbacks of Maximal Adaptation....................................................................................................... 638 25.5.1 Optimal Procedure ............................................................................................... 638 25.5.2 Simulations of Naturally Rearranged Sensory Environments ............................. 638 25.5.3 Potential Drawbacks of Maximal Adaptation ...................................................... 639
25.5.3.1 Negative Aftereffects and Negative Transfer ...................................... 639 25.5.3.2 Eliminating the Aftereffects ................................................................ 639
25.6 Role of Individual Differences ........................................................................................... 641 25.7 Summary and Conclusions .................................................................................................642 References ......................................................................................................................................642
rearrangements, it is reasonable to assume they are equally able to adapt to the sensory rearrangements that occur in VEs. Likewise, the variables found to inªuence adaptation to sensory rearrangements in general, for example, active interaction, should apply as well to VE adaptation. Thus, the VE training procedures described in this chapter are based on the variables demonstrated by previous research to control or inªuence adaptation to rearranged sensory environments. Research indicates that the problematical postexposure aftereffects that inevitably result from VE adaptation can be reduced or eliminated by means of systematic readaptation procedures and dual adaptation training (i.e., repeated alternation between adaptation and readaptation). Finally, the ubiquity of individual differences in adaptation to sensory rearrangements is acknowledged and implications for the individualization of VE adaptation-training procedures considered.
