More than just perception–action recalibration: Walking through a virtual environment causes rescaling of perceived space

Abstract

Egocentric distances in virtual environments are commonly underperceived by up to 50 % of the intended distance. However, a brief period of interaction in which participants walk through the virtual environment while receiving visual feedback can dramatically improve distance judgments. Two experiments were designed to explore whether the increase in postinteraction distance judgments is due to perception-action recalibration or the rescaling of perceived space. Perception-action recalibration as a result of walking interaction should only affect action-specific distance judgments, whereas rescaling of perceived space should affect all distance judgments based on the rescaled percept. Participants made blind-walking distance judgments and verbal size judgments in response to objects in a virtual environment before and after interacting with the environment through either walking (Experiment 1) or reaching (Experiment 2). Size judgments were used to infer perceived distance under the assumption of size-distance invariance, and these served as an implicit measure of perceived distance. Preinteraction walking and size-based distance judgments indicated an underperception of egocentric distance, whereas postinteraction walking and size-based distance judgments both increased as a result of the walking interaction, indicating that walking through the virtual environment with continuous visual feedback caused rescaling of the perceived space. However, interaction with the virtual environment through reaching had no effect on either type of distance judgment, indicating that physical translation through the virtual environment may be necessary for a rescaling of perceived space. Furthermore, the size-based distance and walking distance judgments were highly correlated, even across changes in perceived distance, providing support for the sizedistance invariance hypothesis.Keywords Visual perception . Distance perception . Virtual reality . Action Immersive virtual reality technology has numerous applications, including physical and psychological rehabilitation, education, training, entertainment, and human behavioral research. In order to be fully effective in these applications, virtual environments should be perceived as realistic representations of actual environments. One consistent challenge in creating realistic virtual environments is the tendency for underperception of distances, resulting in virtual environments that appear smaller than their real-world counterparts.In real environments under full-cue viewing, the perception of egocentric distance-the distance from oneself to an object -can be quite accurate. Perceived egocentric distance has been measured in multiple ways, including verbal numerical report (da Silva, 1985;Foley,

Walking through a virtual environment improves perceived size within and beyond the walked space

“…Although the direct relationship between perceived size and distance has been questioned, judged distance and size have been shown to be highly correlated (Gogel, Loomis, Newman, & Sharkey, 1985;Hutchison & Loomis, 2006), presumably due to the impact of perceived distance on both perceptual variables (Brenner & van Damme). Kelly et al (2013) found that object size judgments increased after a walking interaction, consistent with an increase in perceived distance. More recently, Kunz, Creem-Regehr, and Thompson (2015) tested the effects of visual feedback, indicating faster-or slower-than-actual walking speed in a VE.…”

“…One common approach to improving distance perception in VR allows participants to interact with the VE while receiving visual feedback (Kelly, Donaldson, Sjolund & Freiberg, 2013;Kelly, Hammel, Siegel, & Sjolund, 2014;Mohler, Creem-Regehr & Thompson, 2006;Richardson & Waller, 2005, 2007Waller & Richardson, 2008). In a prototypical study by Waller and Richardson (2008), participants performed preinteraction distance judgments, followed by interaction and then postinteraction distance judgments.…”

“…As compared to blind walking, the resizing task served as a measure of perceived distance that should be immune to sensorimotor recalibration during walking interaction. As compared to verbal size judgments (Kelly et al, 2013), the resizing task should not be affected by an individual's skill in assigning metric values, and therefore judgments should be less variable. In light of the equivocal reports on the relationship between walking interaction and perceived size (Kelly et al, 2013;Kunz et al, 2015), the same experiment was conducted twice.…”

Object distance scaling in real space is preserved in low vision subjects

“…Dynamic events also do not help subjects to improve their distance judgment. Subjects in a virtual environment performing a walk task showed that the perception of walked distances were not correlated with their previously distance judged [24]. These authors also found an underestimation of distance to egocentric judgment, a result that is in line with ours.…”

Frontal extents in virtual environments are not immune to underperception

“…The current project compared the relationship between frontal and depth extents in two VEs: the indoor classroom environment used by Geuss et al (2012) and a barren outdoor environment consisting of a ground plane covered in a grass texture, which has produced relatively large underperception of egocentric distance in our laboratory (Kelly, Hammel, Siegel, & Sjolund, 2014). Similar outdoor VEs have been used in numerous experiments testing distance perception (Kelly, Donaldson, Sjolund, & Freiberg, 2013;Li et al, 2013;Messing & Durgin, 2005;Richardson & Waller, 2005;Waller & Richardson, 2008;Wu, He & Ooi, 2007;Ziemer, Plumert, Cremer & Kearney, 2009). We expected that manipulation of the VE (room vs. grass) would affect judgments of depth extents, with smaller judgments in the grass VE compared to the room VE.…”