Vehicle manufacturers and government agencies are considering using vehicle-to-pedestrian (V2P) communication to improve pedestrian safety. However, there are unanswered questions about whether people will heed alerts and warnings presented through a smartphone. We conducted between-subject studies with younger and older adults where they physically crossed a virtual street. They received either permissive alerts (safe to cross), prohibitive warnings (not safe to cross), or no alerts or warnings (control). We found that both older and younger adults were highly likely to heed permissive alerts, even when this meant taking gaps between two vehicles that were smaller than they would typically take on their own. We also found that we could shift participants’ road-crossing behavior toward greater caution when they were only alerted to cross very large gaps between two vehicles. Participants stated that alerts and warnings were useful, but that prohibitive warnings were annoying. These findings give insights into V2P design and pedestrian behavior when smartphone assistance is provided.

This study investigated how people coordinate their decisions and actions with a risky or safe computer-generated agent in a humanoid or non-humanoid form and how this experience influences later behavior when acting alone. In Experiment 1, participants first repeatedly crossed continuous traffic in a virtual environment with a humanoid computer-generated agent (Figure 1). Participants were specifically instructed to cross with an agent that was programmed to be either safe (taking only large gaps) or risky (also taking relatively small gaps). Participants then repeatedly crossed the same roadway alone. We found that participants’ experiences with crossing safe vs. risky gaps with an agent persisted in later trials when the participants crossed alone, such that participants accepted tighter gaps if they were previously paired with a risky than a safe agent. In Experiment 2 (Figure 2), we tested whether experience crossing with a risky or safe non-humanoid object (a floating box) also influenced later behavior when crossing alone. We again found that participants who crossed with the risky object partner took tighter gaps when later crossing alone than those who crossed with the safe object partner. The Discussion focuses on the impact of experiences with virtual agents on perception–action tuning and the potential of using virtual agents for training safe road-crossing behavior.

This paper examines how people jointly coordinate their decisions and actions with risky vs. safe human and agent road-crossing partners (Fig. 1 ). The task for participants was to physically cross a steady stream of traffic in a large-screen virtual environment without getting hit by a car. The computer-generated (CG) agent was programmed to be either safe (taking only large gaps) or risky (also taking small gaps). The human partners were classified as safe (taking more large gaps) or risky (also taking some small gaps) based on their average gap size selection. We found that participants in all four conditions preferred to cross with their partner. As a consequence, the riskiness of the partner (both human and agent) influenced the riskiness of participants' gap choices. We also found that participants tightly synchronized their movement with both human and agent partners. The largest differences in performance between those paired with agent vs. human partners occurred on trials when participants crossed different gaps than their partners. This study demonstrates the potential for studying how people interact with CG agents when performing whole-body joint actions using large-screen immersive virtual environments.

We investigated how two people jointly coordinate their decisions and actions in a co-occupied, large-screen virtual environment. The task for participants was to physically cross a virtual road with continuous traffic without getting hit by a car. Participants performed this task either alone or with another person (see Figure 1). Two separate streams of non-stereo images were generated based on the dynamic locations of the two viewers’ eye-points. Stereo shutter glasses were programmed to display a single image stream to each viewer so that they saw perspectively correct non-stereo images for their eyepoint. We found that participant pairs often crossed the same gap together and closely synchronized their movements when crossing. Pairs also chose larger gaps than individuals, presumably to accommodate the extra time needed to cross through gaps together. These results demonstrate how two people interact and coordinate their behaviors in performing whole-body, joint motions in a co-occupied virtual environment. This study also provides a foundation for future studies examining joint actions in shared VEs where participants are represented by graphic avatars.

This paper investigates the influence of stereoscopic vs. non-stereoscopic display in large-screen virtual environments on an everyday perception-action task - crossing traffic-filled roadways as a pedestrian. The task for participants was to physically cross a virtual road with continuous traffic without getting hit by a car in a CAVE-like virtual environment. Half of the participants performed the task with stereoscopic display and half performed the task with non-stereoscopic display. We found that stereoscopic display had little impact on the size of the gaps participants crossed or the timing of their crossing motion relative to the gap with the exception of a small difference in crossing speed. The results are important for validating the use of non-stereoscopic image displays in ground vehicle simulation and supporting the use of non-stereoscopic displays for multi-viewpoint rendering in co-occupied virtual environments.

This investigation compared how people performed a complex perception-action task - crossing traffic-filled roadways - in a CAVE vs. an HMD virtual environment. Participants physically crossed a virtual roadway with continuous cross traffic in either a CAVE-like or an HTC Vive pedestrian simulator. The 3D model and traffic scenario were identical in both simulators, allowing for a direct comparison between the two display systems. We found that participants in the Vive group accepted smaller gaps for crossing than participants in the CAVE group. They also timed their entry into the gap more precisely and tended to cross somewhat more quickly. As a result, participants in the Vive group had a somewhat larger margin of safety when they exited the roadway than those in the CAVE group. The results provide a foundation for future studies of pedestrian behavior and other tasks involving full-body motion using HMD-based VR.

We investigated how people jointly coordinate their decisions and actions with a computer-generated character (agent) in a large-screen virtual environment. The task for participants was to physically cross a steady stream of traffic on a virtual road without getting hit by a car. Participants performed this task with another person or with a computer-generated character (Fig. 1). The character was programmed to be either safe (taking only large gaps) or risky (also taking relatively small gaps). We found that participants behaved in many respects similarly with real and virtual partners. They maintained similar distances between themselves and their partner, they often crossed the same gap with their partner, and they synchronized their crossing with their partner. We also found that the riskiness of the character influenced the gap choices of participants. This study demonstrates the potential for using large-screen virtual environments to study how people interact with CG characters when performing whole-body joint actions.

We investigated how two people jointly coordinate their decisions and actions in a co-occupied, large-screen virtual environment. The task for participants was to physically cross a virtual road with continuous traffic without getting hit by a car. Participants performed this task either alone or with another person (see Fig.1). We found that pairs often crossed the same gap together and closely synchronized their movements when crossing. Pairs also chose larger gaps than individuals to accommodate the extra time needed to cross through gaps together. These results reveal how two people interact and coordinate their behaviors in performing whole-body, joint motions. This study also provides a foundation for future studies examining joint actions in shared VEs where participants are represented by graphic avatars.

This paper presents an experiment conducted in a large-screen immersive virtual environment to evaluate how texting pedestrians respond to permissive traffic alerts delivered via their cell phone. We developed a cell phone app that delivered information to texting pedestrians about when traffic conditions permit safe crossing. We compared gap selection and movement timing in three groups of pedestrians: texting, texting with alerts, and no texting (control). Participants in the control and alert groups chose larger gaps and were more discriminating in their gap choices than participants in the texting group. Both the control and alert groups had more time to spare than the texting group when they exited the roadway even though the alert group timed their entry relative to the lead car less tightly than the control and texting groups. By choosing larger gaps, participants in the alert group were able to compensate for their poorer timing of entry, resulting in a margin of safety that did not differ from those who were not texting. However, they also relied heavily on the alert system and paid less attention to the roadway. The discussion focuses on the potential of assistive technologies based on Vehicle-to-Pedestrian (V2P) communications technology for mitigating pedestrian-motor vehicle crashes.

We investigated how the properties of interactive virtual reality systems affect user behavior in full-body embodied interactions. Our experiment compared four interactive virtual reality systems using different display types (CAVE vs. HMD) and modes of locomotion (walking vs. joystick). Participants performed a perceptual-motor coordination task, in which they had to choose among a series of opportunities to pass through a gate that cycled open and closed and then board a moving train. Mode of locomotion, but not type of display, affected how participants chose opportunities for action. Both mode of locomotion and display affected performance when participants acted on their choices. We conclude that technological properties of virtual reality system (both display and mode of locomotion) significantly affected opportunities for action available in the environment (affordances) and discuss implications for design and practical applications of immersive interactive systems.

We conducted a series of experiments to investigate effects of scale changes on distance perception in virtual environments. All experiments were carried out in an HMD. Participants first made distance estimates with feedback in a virtual tunnel (adaptation) and then made distance estimates without feedback in a differently-scaled virtual environment (test). We examined several types of scale changes, including changing the size of (1) the tunnel, (2) the targets, and (3) the separation of the two targets. Changes in target size always affected distance estimates at test. When the targets became smaller, participants overshot distance and when the targets became larger, participants undershot distance. Changes in the size of the tunnel or the separation between the targets (without a change in the size of the targets) had a minimal effect on distance estimates. These results indicate that distance estimates at test were strongly influenced by familiar size cues for distance. The discussion focuses on the stability of calibration processes and mechanisms for cue integration for perceiving distance in virtual environments.

The goal of our work is to develop a programmatically controlled peer to bicycle with a human subject for the purpose of studying how social interactions influence road-crossing behavior. The peer is controlled through a combination of reactive controllers that determine the gross motion of the virtual bicycle, action-based controllers that animate the virtual bicyclist and generate verbal behaviors, and a keyboard interface that allows an experimenter to initiate the virtual bicyclist's actions during the course of an experiment. The virtual bicyclist's repertoire of behaviors includes road following, riding alongside the human rider, stopping at intersections, and crossing intersections through specified gaps in traffic. The virtual cyclist engages the human subject through gaze, gesture, and verbal interactions. We describe the structure of the behavior code and report the results of a study examining how 10- and 12-year-old children interact with a peer cyclist that makes either risky or safe choices in selecting gaps in traffic. Results of our study revealed that children who rode with a risky peer were more likely to cross intermediate-sized gaps than children who rode with a safe peer. In addition, children were significantly less likely to stop at the last six intersections after the experience of riding with the risky than the safe peer during the first six intersections. The results of the study and children's reactions to the virtual peer indicate that our virtual peer framework is a promising platform for future behavioral studies of peer influences on children's bicycle riding behavior.

We conducted two experiments that compared distance perception in real and virtual environments in six visual presentation methods using either timed imagined walking or direct blindfolded walking, while controlling for several other factors that could potentially impact distance perception. Our presentation conditions included unencumbered real world, real world seen through an HMD, virtual world seen through an HMD, augmented reality seen through an HMD, virtual world seen on multiple, large immersive screens, and photo-based presentation of the real world seen on multiple, large immersive screens. We found that there was a similar degree of underestimation of distance in the HMD and large-screen presentations of virtual environments. We also found that while wearing the HMD can cause some degree of distance underestimation, this effect depends on the measurement protocol used. Finally, we found that photo-based presentation did not help to improve distance perception in a large-screen immersive display system. The discussion focuses on points of similarity and difference with previous work on distance estimation in real and virtual environments.

The goal of our work is to develop a programmatically controlled peer to ride with a human subject for the purpose of studying how social interactions influence riding behavior. The peer is controlled through a combination of reactive controllers that determine the gross motion of the virtual bicycle, action-based controllers that animate the virtual bicyclist and generate verbal behaviors, and a keyboard interface that allows an experimenter to initiate the virtual bicyclist's actions during the course of an experiment. The virtual bicyclist's repertoire of behaviors includes road following, riding alongside the human rider, stopping at intersections, and crossing intersections through specified gaps. The virtual cyclist engages the human subject through gaze, gesture, and verbal interactions. We describe the structure of the behavior code and report the results of a pilot study examining how 10- and 12-year-old children interact with a peer cyclist. Results of the pilot study showed that the presence of the peer had a significant influence on the size of the gaps taken as well as time left to spare between the participant and the trailing car in the crossed gap.

We conducted three experiments to compare distance perception in real and virtual environments. In Experiment 1, adults estimated how long it would take to walk to targets in real and virtual environments by starting and stopping a stopwatch while looking at a target person standing between 20 and 120 ft away. The real environment was a large grassy lawn in front of a university building. We replicated this scene in our virtual environment using a nonstereoscopic, large-screen immersive display system. We found that people underestimated time to walk in both environments for distances of 40 to 60 ft and beyond. However, time-to-walk estimates were virtually identical across the two environments, particularly when people made real environment estimates first. In Experiment 2, 10- and 12-year-old children and adults estimated time to walk in real and virtual environments both with and without vision. Adults underestimated time to walk in both environments for distances of 60 to 80 ft and beyond. Again, their estimates were virtually identical in the real and virtual environment both with and without vision. Twelve-year-olds' time-to-walk estimates were also very similar across the two environments under both viewing conditions, but 10-year-olds exhibited greater underestimation in the virtual than in the real environment. A third experiment showed that adults' time-to-walk estimates were virtually identical to walking without vision. We conclude that distance perception may be better in virtual environments involving large-screen immersive displays than in those involving head-mounted displays (HMDS).