scholarly journals It’s in your hands: How variable perception affects grasping estimates in virtual reality

2021 ◽  
Author(s):  
Megan Rose Readman ◽  
Dalton Cooper ◽  
Sally A. Linkenauger
Keyword(s):  
Virtual Reality ◽  
Perceptual System ◽  
Motor Variability ◽  
Action Capability ◽  
Motor Experience ◽  
Action Capabilities ◽  
Average Action

AbstractSuccessful interaction within one’s environment is contingent upon one’s ability to accurately perceive the extent over which actions can be performed, referred to as action boundaries. As our possibilities for action are subject to variability, it is necessary for individuals to be able to update their perceived action boundaries to accommodate for variance. While research has shown that individuals can update their action boundaries to accommodate for variability, it is unclear how the perceptual system calibrates to this variance to inform our action boundaries. This study investigated the influence of perceptual motor variability by analysing the effect of random and systematic variability on perceived grasp ability in virtual reality. Participants estimated grasp ability following perceptual-motor experience with a constricted, normal, extended, or variable grasp. In Experiment 1, participants experienced all three grasping abilities (constricted, normal, extended) 33% of the time. In Experiment 2 participants experienced the constricted and normal grasps 25% of the time, and the extended grasp 50% of the time. The results indicated that when perceptual-motor feedback is inconsistent, the perceptual system disregards the frequency of perceptual-motor experience with the different action capabilities and considers each action capability experienced as a type, and subsequently calibrates to the average action boundary experienced by type.

scholarly journals The Influence of Perceptual-Motor Variability on the Perception of Action Boundaries for Reaching in a Real-World Setting

Perception ◽  
2021 ◽  
Vol 50 (9) ◽  
pp. 783-796
Author(s):  
Lisa P. Y. Lin ◽  
Christopher J. Plack ◽  
Sally A. Linkenauger
Keyword(s):  
Virtual Reality ◽  
Real World ◽  
Elbow Extension ◽  
Visually Guided ◽  
Motor Variability ◽  
Real World Setting ◽  
Action Capabilities ◽  
Successful Execution ◽  
Perceptual Systems ◽  
Perception Of Action

The ability to accurately perceive the extent over which one can act is requisite for the successful execution of visually guided actions. Yet, like other outcomes of perceptual-motor experience, our perceived action boundaries are not stagnant, but in constant flux. Hence, the perceptual systems must account for variability in one’s action capabilities in order for the perceiver to determine when they are capable of successfully performing an action. Recent work has found that, after reaching with a virtual arm that varied between short and long each time they reach, individuals determined their perceived action boundaries using the most liberal reaching experience. However, these studies were conducted in virtual reality, and the perceptual systems may handle variability differently in a real-world setting. To test this hypothesis, we created a modified orthopedic elbow brace that mimics injury in the upper limb by restricting elbow extension via remote control. Participants were asked to make reachability judgments after training in which the maximum extent of their reaching ability was either unconstricted, constricted or variable over several calibration trials. Findings from the current study did not conform to those in virtual reality; participants were more conservative with their reachability estimates after experiencing variability in a real-world setting.

scholarly journals Perceiving action boundaries for overhead reaching in a height-related situation

2021 ◽  
Author(s):  
Lisa P. Y. Lin ◽  
Sally A. Linkenauger
Keyword(s):  
Recent Work ◽  
Weighted Average ◽  
Environmental Context ◽  
Perceptual System ◽  
Motor Variability ◽  
Maximum Extent ◽  
Probabilistic Information ◽  
Motor Experience ◽  
Over Time

AbstractTo successfully interact within our environment, individuals need to learn the maximum extent (or minimum) over which they can perform actions, popularly referred to as action boundaries. Because people learn such boundaries over time from perceptual motor feedback across different contexts, both environmental and physiological, the information upon which action boundaries are based must inherently be characterised by variability. With respect to reaching, recent work suggests that regardless of the type of variability present in their perceptual-motor experience, individuals favoured a liberal action boundary for horizontal reaching. However, the ways in which action boundaries are determined following perceptual-motor variability could also vary depending on the environmental context as well as the type of reach employed. The present research aimed to established whether the perceptual system utilises the same strategy for all types of reaches over different contexts. Participants estimated their overhead reachability following experience reaching with either a long or a short virtual arm, or a virtual arm that varied in length – while standing on the edge of a rooftop or standing on the ground. Results indicated that while similar strategies were used to determine action boundaries in both height- and non-height-related context, participants were significantly more conservative with their reachability estimates in the height-related context. Participants were sensitive to the probabilistic information associated with different arm’s reach they have experienced during the calibration phase, and used a weighted average of reaching experience to determine their action boundary under conditions of uncertainty.

Do exploratory arm movements contribute to maximum reach distance judgements?

2020 ◽  
Vol 73 (9) ◽  
pp. 1301-1310
Author(s):  
Keith S Jones ◽  
Benjamin P Widlus
Keyword(s):  
Arm Movements ◽  
Arm Movement ◽  
Movement Restriction ◽  
Action Capability ◽  
Body Armour ◽  
Action Capabilities ◽  
Restricted Condition ◽  
Carry Over ◽  
Exploratory Movements ◽  
Practical Implications

Exploratory movements provide information about agents’ action capabilities in a given environment. However, little is known about the specifics of these exploratory movements, such as which movements are necessary to perceive a given action capability. This experiment tested whether arm movements contributed to judgements of maximum reach distance. Participants made judgements about their maximum reach distance by walking to the point farthest from an object from which they still perceived the object to be reachable. Over the course of two sets of nine judgements, participants’ arms either swung naturally by their sides (Unrestricted Condition) or were held together behind their backs (Restricted Condition). Arm movement restriction increased maximum reach distance judgement error when compared with unrestricted judgements. In addition, judgement error improved over trials only when exploratory arm movements were unrestricted, and the improvements did not carry over to subsequent judgements made when exploratory arm movements were restricted. Arm movement restriction did not increase the variability of judgement error when compared with unrestricted judgements. The results indicate that exploration is necessary to generate affordance information, show that restricted exploration degrades affordance perception, and suggest that maximum reach distance exists at the global array level. In addition, they have practical implications for operational situations in which actors’ arm movements are restricted, such as when military personnel wear body armour.

Tau and Depth Cues Influence the Position of Braking in Virtual Environment

2011 ◽  
Vol 271-273 ◽  
pp. 158-164
Author(s):  
Wei Dong Tao ◽  
Hong Jing Sun
Keyword(s):  
Virtual Reality ◽  
Virtual Environment ◽  
Visual Information ◽  
Perceptual System ◽  
Visual Object ◽  
Virtual Reality Technology ◽  
Depth Cues ◽  
Depth Cue ◽  
Speed Up ◽  
Dilation Rate

To investigate whether both the sources of visual information tau cue and depth cue were utilized to guide braking, in the present study we used the virtual reality technology which could decouple the dilation rate of visual object and depth cue. Participants were instructed to park a car to an obstacle as closely as possible and avoid making collision. Results showed: (1) on the condition of same initial distance from car to an obstacle, participants tended to brake in advance on tau speed-up condition, which caused longer distance from braking to an obstacle than on control condition(tau and depth cue couple);While participants tended to postpone braking on tau speed-down condition, which caused the shorter distance from braking to an obstacle than on control condition; (2) On tau speed-up and tau speed-down condition, participants automatically fine-tuned the actual braking position to avoid making collision. These results suggested that both tau cue and depth cue were processed and utilized to direct the behavior of braking by our visual perceptual system.

scholarly journals Sensory conflict alters visual perception of action capabilities during crossing of a closing gap in virtual reality

2020 ◽  
Vol 73 (12) ◽  
pp. 2309-2316
Author(s):  
Natalie Snyder ◽  
Michael Cinelli
Keyword(s):  
Virtual Reality ◽  
Visual Information ◽  
Sensory Input ◽  
Vestibular Input ◽  
Gait Termination ◽  
Switch Point ◽  
Action Capabilities ◽  
Acceleration And Deceleration ◽  
Locomotion Interface ◽  
Perception Of Action

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.

Movement Strategies in Virtual Reality: Exploring the Influence of 3D Endpoint Variability

2021 ◽  
Vol 65 (1) ◽  
pp. 91-95
Author(s):  
Logan D. Clark ◽  
Sara L. Riggs
Keyword(s):  
Principal Component Analysis ◽  
Virtual Reality ◽  
Principal Component ◽  
Component Analysis ◽  
Movement Behavior ◽  
Motor Variability ◽  
Movement Strategies ◽  
Kinematic Approach

Research using a kinematic approach has revealed that users often exhibit strategic biases in their movement behavior to minimize the effort required to reach a target. However, a recent exploration of these effects in a virtual reality (VR) environment yielded conflicting results, calling into question whether strategic patterns observed in movements to physical targets can be expected to generalize to VR environments. In the present study, we re-analyze the data from Clark and Riggs (2020) using principal component analysis (PCA) to empirically distinguish between alternative explanations for the unexpected results. Our findings clarify the source of these results for downward versus upward movements and provide a preliminary look at how adaptations to manage perception- and execution-related motor variability may impact users’ movement strategies in VR.

scholarly journals The influence of skill and task complexity on perception of nested affordances

2021 ◽  
Author(s):  
Ludovic Seifert ◽  
Matt Dicks ◽  
Frieder Wittmann ◽  
Peter Wolf
Keyword(s):  
Task Complexity ◽  
Skill Level ◽  
Maximum Distance ◽  
Action Capability ◽  
Action Capabilities ◽  
Perception Action ◽  
And Task

AbstractThis study investigated how skill level and task complexity influence the calibration of perception–action and particularly how close an individual acts relative to his or her maximal action capabilities. Complexity was manipulated between two (Touch, Grasp) and more than two (Removing, Moving Up) nested affordance conditions. For all conditions, we examined whether advanced climbers had greater maximal action capabilities than intermediate climbers or whether they better scaled their action (i.e., acted nearer to their maximal action capabilities) or both. Eleven intermediate and 11 advanced male climbers were first asked to estimate the maximum distance that they could reach a climbing hold. The hold was moved along a slide and fixed once requested by the participant; subsequently, the distance to the starting hold was measured. After each estimation, the participant was required to execute the climbing action. After four estimation-action trials in each of the four conditions, the maximal action capability (i.e., actual maximal reaching distance) was determined. Advanced climbers demonstrated greater actual maximal reaching distances than intermediate climbers for all conditions, but they only estimated greater maximal reaching distances for the more complex conditions, which featured more than two nested affordances. When estimated maximal reaching distances were scaled to actual maximal reaching distances, advanced climbers did not differ from intermediate climbers for any condition, and there were no differences between conditions. Our findings indicate that expertise was a function of greater action capabilities, but not due to the accuracy of calibration.

scholarly journals How far can I reach? The perception of upper body action capabilities in Parkinson’s disease

2021 ◽  
Author(s):  
Megan Rose Readman ◽  
Neil M. McLatchie ◽  
Ellen Poliakoff ◽  
Trevor J. Crawford ◽  
Sally A. Linkenauger
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Upper Body ◽  
Healthy Controls ◽  
Healthy Older Adults ◽  
Motor Abilities ◽  
Motor Experience ◽  
Action Capabilities ◽  
Passing Ability ◽  
Over Time

AbstractSuccessful interaction within the environment is contingent upon one’s ability to accurately perceive the extent over which they can successfully perform actions, known as action boundaries. Healthy young adults are accurate in estimating their action boundaries and can flexibly update them to accommodate stable changes in their action capabilities. However, there are conditions in which motor abilities are subject to variability over time such as in Parkinson’s disease (PD). PD impairs the ability to perform actions and can lead to variability in perceptual-motor experience, but the effect on the perceptions of their action boundaries remains unknown. This study investigated the influence of altered perceptual-motor experience during PD, on the perceptions of action boundaries for reaching, grasping, and aperture passing. Thirty participants with mild-to-moderate idiopathic PD and 26 healthy older adults provided estimates of their reaching, grasping, and aperture-passing ability. Participants’ estimates were compared with their actual capabilities. There was no evidence that individuals with PD’s perceptions were less accurate than those of healthy controls. Furthermore, there was some evidence for more conservative estimates than seen in young healthy adults in reaching (both groups) and aperture passing (PD group). This suggests that the ability to judge action capabilities is preserved in mild to moderate PD.

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