A review of grasping as the movements of digits in space

Smeets, Jeroen B. J.; Kooij, Katinka van der; Brenner, Eli

doi:10.1152/jn.00123.2019

Cited by 28 publications

(24 citation statements)

References 209 publications

(292 reference statements)

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“…Our finding that the haptic position cue reduces the grip aperture and increases movement velocity even in conditions of full binocular vision instead suggests that vision-for-action is less efficient than it is usually claimed. Second, our finding that holding the pole on which the object is placed (i.e., only haptic position cue available) leads to identical grasping performance as when both haptic size and position cues are available is not fully compatible with the theories about grasping that propose that either a single digit (Galea, Castiello, & Dalwood, 2001; Haggard & Wing, 1997; Melmoth & Grant, 2012; Mon-Williams & McIntosh, 2000; Wing & Fraser, 1983) or both digits (Schot, Brenner, & Smeets, 2017; Smeets & Brenner, 1999; Smeets, van der Kooij, & Brenner, 2019) are transported to specific positions on the object. In the VHP condition, the positions on the object toward which the fingers were moving (grasping points) did not coincide with the haptic positions felt by the fingers of the left hand.…”

Section: Discussioncontrasting

confidence: 62%

Integration of haptics and vision in human multisensory grasping

Camponogara

Volcic

2020

Preprint

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Grasping actions are directed not only toward objects we see but also toward objects we both see and touch (multisensory grasping). In this latter case, the integration of visual and haptic inputs improves movement performance compared to each sense alone. This performance advantage could be due to the integration of all the redundant positional and size cues or to the integration of only a subset of these cues. Here we selectively provided specific cues to tease apart how these different sensory sources contribute to visuo-haptic multisensory grasping. We demonstrate that the availability of the haptic positional cue together with the visual cues is sufficient to achieve the same grasping performance as when all cues are available. These findings provide strong evidence that the human sensorimotor system relies on non-visual sensory inputs and open new perspectives on their role in supporting vision during both development and adulthood.

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Section: Discussioncontrasting

confidence: 62%

Integration of haptics and vision in human multisensory grasping

Camponogara

Volcic

2020

Preprint

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“…Turning away from models of cue reweighting, an important final discussion point involves our generic assumption that estimates of 3D shape properties ( i.e., surface slant and object depth) are, in fact, the inputs to the motor planning processes involved in our visuomotor tasks. In contrast to this assumption, Smeets and Brenner [40, 41] have notably defended an elegant alternative model of precision-grip control in which thumb and index finger movements are planned as two independent pointing movements aimed at two separate egocentric locations. Their model provides another possible way to explain the apparent stereo preference in visuomotor tasks involving 3D stimuli.…”

Section: Discussionmentioning

confidence: 99%

Sensorimotor adaptation compensates for distortions of 3D shape information

Cesanek

Taylor

Domini

2019

Preprint

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Visual perception often fails to recover the veridical 3D shape of objects in the environment due to ambiguity and variability in the available depth cues. However, we rely heavily on 3D shape estimates when planning movements, for example reaching to pick up an object from a slanted surface. Given the wide variety of distortions that can affect 3D perception, how do our actions remain accurate across different environments? One hypothesis is that the visuomotor system performs selective filtering of 3D information to minimize distortions. Indeed, some studies have found that actions appear to preferentially target stereo information when it is put in conflict with texture information. However, since these studies analyze averages over multiple trials, this apparent preference could be produced by sensorimotor adaptation. In Experiment 1, we create a set of cue-conflict stimuli where one available depth cue is affected by a constant bias. Sensory feedback rapidly aligns the motor output with physical reality in just a few trials, which can make it seem as if action planning selectively relies on the reinforced cue—yet no change in the relative influences of the cues is necessary to eliminate the constant errors. In contrast, when one depth cue becomes less correlated with physical reality, variable movement errors will occur, causing canonical adaptation to fail as the opposite error corrections cancel out. As a result, canonical adaptation cannot explain the preference for stereo found in studies with variable errors. However, Experiment 2 shows that persistent errors can produce a novel form of adaptation that gradually reduces the relative influence of an unreliable depth cue. These findings show that grasp control processes are continuously modified based on sensory feedback to compensate for both biases and noise in 3D visual processing, rather than having a hardwired preference for one type of depth information.

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“…We note, however, that while the current results are consistent with this simple, double-pointing account, this proposal is not in line with previous evidence about 2D grasping, a task, which arguably should also involve directing the digits at two discrete locations. However, simple interactions with 2D objects (as well as with 3D virtual objects in Experiment 1) typically obey perceptual regularities ( Holmes and Heath, 2013 ; Freud and Ganel, 2015 ; Ozana and Ganel, 2018 , 2019a ), which goes against a simple double pointing strategy account (but see, Smeets et al, 2019 ).…”

Section: Discussionmentioning

confidence: 88%

“…According to this account, grasping depends on independently pointing each digit to a different location, rather than encoding the object size. Indeed, this model could potentially explain why perceptual regularities about object size and context typically do not affect visuomotor control ( Smeets et al, 2019 ). We note, however, that while the current results are consistent with this simple, double-pointing account, this proposal is not in line with previous evidence about 2D grasping, a task, which arguably should also involve directing the digits at two discrete locations.…”

Section: Discussionmentioning

confidence: 99%

Grasping Weber’s Law in a Virtual Environment: The Effect of Haptic Feedback

2020

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Recent findings suggest that the functional separation between vision-for-action and vision-for-perception does not generalize to situations in which virtual objects are used as targets. For instance, unlike actions toward real objects that violate Weber's law, a basic law of visual perception, actions toward virtual objects presented on flat-screens, or in remote virtual environments, obey to Weber's law. These results suggest that actions in virtual environments are performed in an inefficient manner and are subjected to perceptual effects. It is unclear, however, whether this inefficiency reflects extensive variation in the way in which visual information is processed in virtual environments or more local aspects related to the settings of the virtual environment. In the current study, we focused on grasping performance in a state-of-the-art virtual reality system that provides an accurate representation of the 3D space. Within this environment, we tested the effect of haptic feedback on grasping trajectories. Participants were asked to perform bimanual grasping movements toward the edges of virtual targets. In the haptic feedback condition, physical stimuli of matching dimensions were embedded in the virtual environment. Haptic feedback was not provided in the no-feedback condition. The results showed that grasping trajectories in the feedback, but not in the no-feedback condition, could be performed more efficiently, and evade the influence of Weber's law. These findings are discussed in relevance to previous literature on 2D and 3D grasping.

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A review of grasping as the movements of digits in space

Abstract: Smeets JBJ, van der Kooij K, Brenner E. A review of grasping as the movements of digits in space.

Cited by 28 publications

References 209 publications

Integration of haptics and vision in human multisensory grasping

Integration of haptics and vision in human multisensory grasping

Sensorimotor adaptation compensates for distortions of 3D shape information

Grasping Weber’s Law in a Virtual Environment: The Effect of Haptic Feedback

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