Pantomime-Grasping: Advance Knowledge of Haptic Feedback Availability Supports an Absolute Visuo-Haptic Calibration

Jazi, Shirin Davarpanah; Heath, Matthew

doi:10.3389/fnhum.2016.00197

Cited by 19 publications

(13 citation statements)

References 59 publications

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“…Our findings are consistent with those from a previous investigation that tested memory-guided pantomime grasps directed at the remembered location of a previewed object with and without haptic feedback (Davarpanah Jazi and Heath, 2016). In the haptic-feedback condition, after the participants completed their pantomime grasp, the previewed target was placed between their thumb and index finger.…”

Section: Discussionsupporting

confidence: 91%

“…The haptic and no-haptic conditions were blocked separately or randomly interleaved and left uncued. The authors found that grip aperture violated Weber's law, which has been adopted as index of absolute vs. relative coding of target size (e.g., Ganel et al, 2008;Holmes et al, 2013;Manzone et al, 2017;Ozana and Ganel, 2018b; but see Foster and Franz, 2013;Löwenkamp et al, 2015), for the haptic conditions only when blocked separately (Davarpanah Jazi and Heath, 2016). It is unknown, however, whether their findings are due to a cued expectation for haptic feedback or to visuo-haptic calibration, because the authors did not test a cued variant of their randomized haptic schedule.…”

Section: Discussionmentioning

confidence: 99%

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The Role of Haptic Expectations in Reaching to Grasp: From Pantomime to Natural Grasps and Back Again

et al. 2020

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When we reach to pick up an object, our actions are effortlessly informed by the object’s spatial information, the position of our limbs, stored knowledge of the object’s material properties, and what we want to do with the object. A substantial body of evidence suggests that grasps are under the control of “automatic, unconscious” sensorimotor modules housed in the “dorsal stream” of the posterior parietal cortex. Visual online feedback has a strong effect on the hand’s in-flight grasp aperture. Previous work of ours exploited this effect to show that grasps are refractory to cued expectations for visual feedback. Nonetheless, when we reach out to pretend to grasp an object (pantomime grasp), our actions are performed with greater cognitive effort and they engage structures outside of the dorsal stream, including the ventral stream. Here we ask whether our previous finding would extend to cued expectations for haptic feedback. Our method involved a mirror apparatus that allowed participants to see a “virtual” target cylinder as a reflection in the mirror at the start of all trials. On “haptic feedback” trials, participants reached behind the mirror to grasp a size-matched cylinder, spatially coincident with the virtual one. On “no-haptic feedback” trials, participants reached behind the mirror and grasped into “thin air” because no cylinder was present. To manipulate haptic expectation, we organized the haptic conditions into blocked, alternating, and randomized schedules with and without verbal cues about the availability of haptic feedback. Replicating earlier work, we found the strongest haptic effects with the blocked schedules and the weakest effects in the randomized uncued schedule. Crucially, the haptic effects in the cued randomized schedule was intermediate. An analysis of the influence of the upcoming and immediately preceding haptic feedback condition in the cued and uncued random schedules showed that cuing the upcoming haptic condition shifted the haptic influence on grip aperture from the immediately preceding trial to the upcoming trial. These findings indicate that, unlike cues to the availability of visual feedback, participants take advantage of cues to the availability of haptic feedback, flexibly engaging pantomime, and natural modes of grasping to optimize the movement.

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Section: Discussionsupporting

confidence: 91%

Section: Discussionmentioning

confidence: 99%

The Role of Haptic Expectations in Reaching to Grasp: From Pantomime to Natural Grasps and Back Again

et al. 2020

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“…In grasping, the JND is measured as the within-participant variability of the maximal finger aperture during the reach-tograsp movement and it remains invariant with object size, in violation of Weber's law (Ganel et al, 2008). Several experimentally confirmed hypotheses have been suggested for explaining this phenomenon (Smeets and Brenner, 2008;Jazi et al, 2015;Löwenkamp et al, 2015;Utz et al, 2015;Jazi and Heath, 2016).…”

mentioning

confidence: 99%

Visuomotor Resolution in Telerobotic Grasping with Transmission Delays

et al. 2017

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Weber's law is among the basic psychophysical laws of human perception. It determines that human sensitivity to change along a physical dimension, the just noticeable difference (JND), is linearly related to stimulus intensity. Conversely, in direct (natural), visually guided grasping, Weber's law is violated and the JND does not depend on stimulus intensity. The current work examines adherence to Weber's law in telerobotic grasping. In direct grasping, perception and action are synchronized during task performance. Conversely, in telerobotic control, there is an inherent spatial and temporal separation between perception and action. The understanding of perception-action association in such conditions may facilitate development of objective measures for telerobotic systems and contribute to improved interface design. Moreover, telerobotic systems offer a unique platform for examining underlying causes for the violation of Weber's law during direct grasping. We examined whether, like direct grasping, telerobotic grasping with transmission delays violates Weber's law. To this end, we examined perceptual assessment, grasp control, and grasp demonstration, using a telerobotic system with time delays in two spatial orientations: alongside and facing the robot. The examination framework was adapted to telerobotics from the framework used for examining Weber's law in direct grasping. The variability of final grip apertures (FGAs) in perceptual assessment increased with object size in adherence with Weber's law. Similarly, the variability of maximal grip apertures in grasp demonstration approached significance in adherence with Weber's law. In grasp control, the variability of maximal grip apertures did not increase with object size, which seems to violate Weber's law. However, unlike in direct grasping, motion trajectories were prolonged and fragmented, and included an atypical waiting period prior to finger closure. Therefore, in this condition, maximal grip aperture was an inappropriate indicator of JND. Instead, we calculated the aperture at the end of the opening phase, the initial grip aperture (IGA), and the FGA at the beginning of the waiting period, as more appropriate indicators for the JNDs. The IGAs adhered to Weber's law. The FGAs approached significance in the same direction. This suggests that perception-action association during telerobotic grasping with transmission delays significantly diverges from direct grasping.

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“…It is therefore not surprising that withholding information about the contact points or how they can be reached can influence the whole grasping movement. This has been demonstrated for haptic information (Cuijpers et al 2008;Schenk 2012;Davarpanah Jazi and Heath 2016) as well as for visual information Bozzacchi et al 2018). We therefore designed our set-up in a manner that provided our participants with both visual and haptic feedback near the point of contact, despite restricting the visual feedback to the last part of the digits' trajectories.…”

Section: Discussionmentioning

confidence: 99%

Why some size illusions affect grip aperture

Smeets

Meijden

Brenner

2019

Preprint

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There is an extensive literature debating whether perceived size is used to guide grasping. A possible reason for not using judged size is that using judged positions might lead to more precise movements. As this argument does not hold for small objects, and all studies showing an effect of the Ebbinghaus illusion on grasping used small objects, we hypothesized that size information is used for small objects but not for large ones. Using a modified diagonal illusion, we obtained an effect of about 10% on perceptual judgements, without an effect on grasping, irrespective of object size. We therefore reject our precision hypothesis. We discuss the results in the framework of grasping as moving digits to positions on an object. We conclude that the reported disagreement on the effect of illusions is because the Ebbinghaus illusion not only affects size, but -unlike most size illusions-also affects perceived positions.

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Pantomime-Grasping: Advance Knowledge of Haptic Feedback Availability Supports an Absolute Visuo-Haptic Calibration

Cited by 19 publications

References 59 publications

The Role of Haptic Expectations in Reaching to Grasp: From Pantomime to Natural Grasps and Back Again

The Role of Haptic Expectations in Reaching to Grasp: From Pantomime to Natural Grasps and Back Again

Visuomotor Resolution in Telerobotic Grasping with Transmission Delays

Why some size illusions affect grip aperture

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