Few experiments have been performed to investigate near-field egocentric distance estimation in an Immersive Virtual Environment (IVE) as compared to the Real World (RW). This article investigates near-field distance estimation in IVEs and RW conditions using physical reach and verbal report measures, by using an apparatus similar to that used by Bingham and Pagano [1998]. Analysis of our experiment shows distance compression in both the IVE and RW conditions in participants' perceptual judgments to targets. This is consistent with previous research in both action space in an IVE and reach space with Augmented Reality (AR). Analysis of verbal responses from participants revealed that participants underestimated significantly less in the virtual world as compared to the RW. We also found that verbal reports and reaches provided different results in both IVEs and RW environments.

Distances are regularly underestimated in immersive virtual environments (IVEs) [Witmer and Kline 1998;Loomis and Knapp 2003]. Few experiments, however, have examined the ability of calibration to overcome distortions of depth perception in IVEs. This experiment is designed to examine the effect of calibration via haptic and visual feedback on distance estimates in an IVE. Participants provided verbal and physical reach responses to target distances presented during three sessions; a baseline measure without feedback, a calibration session with visual and haptic feedback, and finally a post-calibration session without feedback. Feedback was shown to calibrate distance estimates within an IVE. Discussion focused on the possibility that costly solutions and research endeavors seeking to remedy the compression of distances may become less necessary if users are simply given the opportunity to use manual activity to calibrate to the IVE.

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Research in visuo-motor coupling has shown that the matching of visual and proprioceptive information is important for calibrating movement. Many state-of-the art virtual reality (VR) systems, commonly known as immersive virtual environments (IVE), are created for training users in tasks that require accurate manual dexterity. Unfortunately, these systems can suffer from technical limitations that may force de-coupling of visual and proprioceptive information due to interference, latency, and tracking error. We present an empirical evaluation of how visually distorted movements affects users' reach to near field targets using a closed-loop physical reach task in an IVE. We specifically examined the recalibration of movements when the visually reached distance is scaled differently than the physically reached distance. Subjects were randomly assigned to one of three visual feedback conditions during which they reached to target while holding a tracked stylus: i) Condition 1 (-20% gain condition) in which the visual stylus appeared at 80% of the distance of the physical stylus, ii) Condition 2 (0% or no gain condition) in which the visual stylus was co-located with the physical stylus, and iii) Condition 3 (+20% gain condition) in which the visual stylus appeared at 120% of the distance of the physical stylus. In all conditions, there is evidence of visuo-motor calibration in that users' accuracy in physically reaching to the target locations improved over trials. During closed-loop physical reach responses, participants generally tended to physically reach farther in condition 1 and closer in condition 3 to the perceived location of the targets, as compared to condition 2 in which participants' physical reach was more accurate to the perceived location of the target.

Two experiments employed attunement and calibration training to investigate whether observers are able to identify material break points in compliant materials through haptic force application. The task required participants to attune to a recently identified haptic invariant, distance-to-break (DTB), rather than haptic stimulation not related to the invariant, including friction. In the first experiment participants probed simulated force-displacement relationships (materials) under 3 levels of friction with the aim of pushing as far as possible into the materials without breaking them. In a second experiment a different set of participants pulled on the materials. Results revealed that participants are sensitive to DTB for both pushing and pulling, even in the presence of varying levels of friction, and this sensitivity can be improved through training. The results suggest that the simultaneous presence of friction may assist participants in perceiving DTB. Potential applications include the development of haptic training programs for minimally invasive (laparoscopic) surgery to reduce accidental tissue damage. (PsycINFO Database Record