Search

The somatosensory, vestibular, and visual systems contribute to multisensory integration, which facilitates locomotion around obstacles in the environment. The joystick-controlled virtual reality (VR) locomotion interface does not preserve congruent sensory input like real-walking, yet is commonly used in human behaviour research. Our purpose was to determine if collision avoidance behaviours were affected during an aperture crossing task when somatosensory and vestibular input were incongruent, and only vision was accurate. Participants included 36 young adults who completed a closing gap aperture crossing task in VR using real-walking and joystick-controlled locomotion. Participants successfully completed the task using both interfaces. Switch point between passable and impassable apertures was larger for joystick-controlled locomotion compared with real-walking, but time-to-contact (TTC) was lower for real-walking than joystick-controlled locomotion. Increased joystick-controlled locomotion switch point may be attributed to incongruency between visual and non-visual information, causing underestimation of distance travelled towards the aperture. Performance on future VR applications incorporating dynamically changing gaps can be considered successful using joystick-controlled locomotion, while taking into account a potential behaviour difference. Differences in TTC may be explained by the requirement of gait termination in real-walking but not in joystick-controlled locomotion. Future VR studies would benefit from programming acceleration and deceleration into joystick-controlled locomotion interfaces. [ABSTRACT FROM AUTHOR]

The purpose of this study was to determine the effects of galvanic vestibular stimulation (GVS) on path trajectory and body rotation during a triangle completion task. Participants (N = 17, female, 18-30 years) completed the triangle completion task in virtual reality using two different size triangles. GVS was delivered at three times each participant's threshold in either the left or right direction prior to the final leg of the triangle and continued until the participant reached their final position. Whole body kinematics were collected using an NDI Optotrak motion tracking system. Results revealed a significant main effect of GVS on arrival error such that no GVS (NGVS) had significantly smaller arrival errors than when GVS was administered. There was also a significant main effect of GVS on angular error such that NGVS had significantly smaller error than GVSaway and GVStowards. There was no significant difference between GVS trials in path variability during the final leg on route to the final position. These results demonstrate that vestibular perturbation reduced the accuracy of the triangle completion task, affecting path trajectory and body position during a path integration task in the absence of visual cues. [ABSTRACT FROM AUTHOR]

Walking through cluttered environments is a requirement of everyday locomotion, and individuals will walk toward open space and adjust their actions in order to prevent injury. When walking in aconfinedspace, individuals require a shoulder rotation to pass through apertures smaller than 1.3 times their shoulder widths. The current study aimed to identify the action strategies employed by young adults to avoid contacting two obstacles placed in the travel path when walking in anonconfinedspace. Participants (N =12) walked along a 10-m path towards a goal while avoiding two vertical obstacles specifically placed to create an aperture (of 0.6 to 1.8 times the participants' shoulder widths) on opposite sides of the travel path midline. Results showed that participants walked around obstacles that were separated by less than 1.4 times their shoulder width (i.e.,critical point). When participants deviated from their initial travel path, they did so by maintaining a consistent protective zone, regardless of the aperture width. The protective zone had dimensions of 3.80 m in the plane of progression and of 0.30 m between themselves and the obstacles at the time of crossing. This study demonstrates that individuals use body-scaled information to control actions in nonconfined space similar to that used in confined space. [ABSTRACT FROM AUTHOR]

The objectives of the current study were: (a) to determine whether perception-action coupling controlled behaviours when walking through moving doors and (b) to determine how vision contributed to this behaviour. Participants (N = 6) walked along a 7-m path toward two motor-driven doors, which moved at rates ranging between 20 and 40 cm/s. Each door was independently driven such that both moved at the same velocity (symmetrical) or at different velocities (asymmetrical). The results showed that in both door movement conditions the participants controlled their approach velocity by slowing down prior to crossing the doors. The decrease in walking velocity produced greater velocity variability in the final stages prior to crossing the doors and high success rates. The results from the gaze behaviours showed that fixation durations were significantly longer when the doors moved asymmetrically, suggesting that the visual information from this unpredictable environment took longer to process. However, the fixation patterns were similar between the two door movement conditions. Regardless of the door movement condition, the participants spent about 60% of each trial fixating environmental objects (i.e., left door, right door, or aperture). The majority of fixations were directed towards one of the doors at the beginning of the trial and then shifted towards the aperture in the final phase. The participants were using perception-action coupling to control their behaviours in the final phase in order to steer locomotion through the aperture. [ABSTRACT FROM AUTHOR]