Examining the Effects of Postural Constraints on Estimating Reach

Gabbard, Carl; Cordova, Alberto; Lee, Sunghan

doi:10.3200/jmbr.39.4.242-246

Cited by 39 publications

(46 citation statements)

References 19 publications

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“…Studies have also shown that the estimation of reachability of a target depends on the posture prior to performing the reach. For example a secure seated posture leading to overestimation vs an unstable standing on one foot posture leading to underestimation (Gabbard et al, 2007). Mantel et al have shown that ultimately, i.e., when no hint can help, it is necessary to move the viewpoint to determine the relative distance to a target of unknown size (Mantel et al, 2005).…”

Section: Full-body Interactionsmentioning

confidence: 99%

On scaling strategies for the full-body postural control of virtual mannequins

Boulic¹,

Maupu²,

Thalmann³

2009

Interacting with Computers

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a b s t r a c tDue to its intrinsic complexity, full-body postural input has been mostly limited to off-line motion capture and to on-line puppetry of a virtual character with little interaction with its environment (e.g. floor). The motion capture technology is now mature enough to envision the on-line full-body postural control of virtual mannequins involved in precise reaching tasks. We have investigated such tasks for mannequins of differing body heights in comparison to that of the system user. Such broad-range avatar control is relevant for virtual prototyping in various industrial sectors as a single person is responsible for evaluating a virtual prototype for a full range of potential end-users. In the present paper we report on two scaling strategies that can be enforced in such a context of height-differing avatar control. Both scaling strategies have been evaluated in a wide-range reach study both in front of a stationary immersive display and with an HMD. A comparison is also made with a baseline scenario, which exploits a simple rigid shape (i.e. a proxy), to assess the specific influence of controlling a complex articulated avatar.

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Section: Full-body Interactionsmentioning

confidence: 99%

On scaling strategies for the full-body postural control of virtual mannequins

Boulic¹,

Maupu²,

Thalmann³

2009

Interacting with Computers

View full text Add to dashboard Cite

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“…For instance, cerebral or corticospinal activation during imagery can be modulated by immobilising a limb (Kaneko et al, 2003), or by a limb posture that is incompatible with the imaged action (De Lange et al, 2006;Vargas et al, 2004). Also, the level of postural demand (e.g., sitting versus standing) have been found to modulate errors in manual reach estimation in young and older adults-greater postural demand in standing posture reverses the tendency to overestimate reaching ability, demonstrating the incorporation of postural constraints into the trajectory planning involved in manual motor imagery (Cordova and Gabbard, 2014;Gabbard and Cordova, 2007). Following the internal model framework, Figure 1 schematises possible routes of information flow during motor imagery.…”

Section: Introductionmentioning

confidence: 99%

Incomplete inhibition of central postural commands during manual motor imagery

Boulton

Mitra

2015

Brain Research

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Imagined movements exhibit many of the behavioral and neurophysiological characteristics of executed actions. As a result, they are considered simulations of physical actions with an inhibition mechanism that suppresses overt movement. This inhibition is incomplete, as it does not block autonomic preparation, and it also does not effectively suppress postural adjustments planned in support of imagined movements. It has been suggested that a central inhibition command may fail to suppress postural adjustments because it may not have access to afference-based elaborations of the postural response that occur downstream of central motor planning.Here, we measured changes in the postural response associated with imagining manual reaching movements under varying levels of imagined loading of the arm. We also manipulated stance stability, and found that postural sway reduced with increased (imagined) arm loading when imagining reaching movements from the less stable stance. As there were no afferent signals associated with the loading constraint, these results suggest that postural adjustments can leak during motor imagery because the postural component of the central motor plan is itself not inhibited effectively.

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“…In the past, many studies have shown that people are quite accurate in visually delimiting their peripersonal space (e.g., Bootsma, Bakker, van Snippenberg, & Tdlohreg, 1992;Bourgeois & Coello, 2009;Carello et al, 1989;Coello & Iwanow, 2006;Fischer, 2000;Gabbard, Ammar, & Lee, 2006;Rochat & Wraga, 1997), although perceptual estimates of reachability have been found to be influenced by environmental context (Coello & Iwanow, 2006), emotional state (Kennedy, Gläscher, Tyszka, & Adolphs, 2009), and postural constraints (Fischer, 2000;Gabbard, Cordova, & Lee, 2007;Rochat & Wraga 1997), as well as mental or neurological illness (Coello & Delevoye-Turrell, 2007;Delevoye-Turrell, Vienne, & Coello, 2011).…”

Section: Introductionmentioning

confidence: 99%

Effect of visuomotor calibration and uncertainty on the perception of peripersonal space

Bourgeois

Yann

2012

Atten Percept Psychophys

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Target selection for action depends not only on the egocentric location of objects estimated from retinal and extraretinal variables, but also on the assessment of current action possibilities. In the present study, we investigated the effect of altering sensorimotor anticipation processes on subsequent perceptual estimates of reachability. To do so, we conducted two experiments in which we changed the relation between visual distance and movement amplitude. Experiment 1 showed that iterative visuomotor adaptation to distorted visual feedback (in steps of ±15 mm, up to a total adaptation of ±75 mm) led to a congruent variation of perceived reachable space, although the first introduction of the shifted visual feedback produced a reduction of perceived reachable space whatever the direction of the feedback shift. Experiment 2 showed that increasing uncertainty about visuomotor performances, by providing a visual feedback randomly shifted in depth (±7.5 mm), produced the same reduction of perceived reachable space in the absence of visuomotor adaptation. Taken together, these data suggest that the visual perception of reachable space depends on a motor-related perceptual system, which is affected by both visuomotor recalibration and reliability of the visuomotor system.

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Examining the Effects of Postural Constraints on Estimating Reach

Cited by 39 publications

References 19 publications

On scaling strategies for the full-body postural control of virtual mannequins

On scaling strategies for the full-body postural control of virtual mannequins

Incomplete inhibition of central postural commands during manual motor imagery

Effect of visuomotor calibration and uncertainty on the perception of peripersonal space

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