Effects of object shape on the visual guidance of action

Eloka, Owino; Franz, Volker H.

doi:10.1167/10.7.1089

Cited by 4 publications

(7 citation statements)

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“…Consistent with these findings, the MGA/ FGA ratio in our experiments was lower than would be expected for grasping of real objects. We observed an average MGA/FGA ratio of 1.2, while studies of actual grasping have observed MGA/FGA ratios of around 1.4-1.7 for objects with similar size (e.g., Eloka and Franz 2011;Westwood et al 2002;Voudouris et al 2013). Thus, there are at least some differences between the movement of the hand during virtual grasping and grasping real objects.…”

Section: Real Versus Virtual Grasping Taskmentioning

confidence: 51%

“…Eloka and Franz (2011) tested conditions in which a disk-shaped target changed to a bar during a grasping movement or vice versa. With no perturbations, subjects showed larger maximum grip aperture when reaching to grasp a bar than when reaching to grasp a disk with matched width.…”

Section: Previous Studies Of Online Control Of Reaching and Graspingmentioning

confidence: 99%

“…Both Ansuini et al (2007) and Eloka and Franz (2011) used a limited set of symmetric objects, and the perturbations required changes in grip aperture rather than change in the orientation of the grasp axis. Thus, the perturbation responses might not reflect the use of shape information to determine appropriate contact points that satisfy physical and postural constraints.…”

Section: °Fmentioning

confidence: 99%

“…Some other recent studies have observed online corrections of grasping movements in response to perturbations of object orientation (Fan et al 2006;Voudouris et al 2013) and object shape (Ansuini et al 2007;Eloka and Franz 2011). These studies used objects with simple, symmetric shapes.…”

Section: Online Determination Of Grasp Pointsmentioning

confidence: 99%

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Online processing of shape information for control of grasping

Chen

Saunders

2015

Exp Brain Res

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When picking up objects, we tend to grasp at contact points that minimize slippage and torsion, which depend on the particular shape. Normally, grasp points could be planned before initiating movement. We tested whether grasp points can be determined during online control. Subjects reached to grasp virtual planar objects with varied shapes. On some trials, the object was changed during movement, either rotated by 45° or replaced with a different object. In all conditions, grasp axes were well adapted to the target shape, passing near the center of mass with low force closure angles. On perturbed trials, corrective adjustments were detectable within 320 ms and were toward the same grasp axes observed on unperturbed trials. Perturbations had little effect on either kinematics or the optimality of final grasp points. Our results demonstrate that the visuomotor system is capable of online processing of shape information to determine appropriate contact points for grasping.

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Section: Real Versus Virtual Grasping Taskmentioning

confidence: 51%

Section: Previous Studies Of Online Control Of Reaching and Graspingmentioning

confidence: 99%

Section: °Fmentioning

confidence: 99%

Section: Online Determination Of Grasp Pointsmentioning

confidence: 99%

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Online processing of shape information for control of grasping

Chen

Saunders

2015

Exp Brain Res

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“…A computer monitor (EIZO Foris FG2421, 23.5", 100 Hz, 1920 pixel x 1080 pixel) was mounted on top of a metal frame in portrait mode, with the screen facing down towards a two-way (semi-transparent) mirror (56 cm x 40 cm) that was placed halfway (34 cm) between the monitor and the work surface. Participants looked into the mirror and perceived the virtual targets shown on the monitor as if positioned on the work surface below the mirror (for description of a similar setup see also Eloka & Franz, 2011).…”

Section: Setup and Stimulimentioning

confidence: 99%

Visual information about object size and object position are retained differently in the visual brain: Evidence from grasping studies

2016

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Many experiments have examined how the visual information used for action control is represented in our brain, and whether or not visually-guided and memory-guided hand movements rely on dissociable visual representations that are processed in different brain areas (dorsal vs. ventral). However, little is known about how these representations decay over longer time periods and whether or not different visual properties are retained in a similar fashion. In three experiments we investigated how information about object size and object position affect grasping as visual memory demands increase. We found that position information decayed rapidly with increasing delays between viewing the object and initiating subsequent actionsimpacting both the accuracy of the transport component (lower end-point accuracy) and the grasp component (larger grip apertures) of the movement. In contrast, grip apertures and fingertip forces remained well-adjusted to target size in conditions in which positional information was either irrelevant or provided, regardless of delay, indicating that object size is encoded in a more stable manner than object position. The findings provide evidence that different grasp-relevant properties are encoded differently by the visual system. Furthermore, we argue that caution is required when making inferences about object size representations based on alterations in the grip component as these variations are confounded with the accuracy with which object position is represented. Instead fingertip forces seem to provide a reliable and confound-free measure to assess internal size estimations in conditions of increased visual uncertainty.

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The Effect of Contour Closure on Shape Recognition

Garrigan

2012

Perception

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Recent research on the Gestalt principle of closure has focused on how the presence of closure affects the ability to detect contours hidden in cluttered visual arrays. Some of the earliest research on closure, however, dealt with encoding and recognizing closed and open shapes, rather than detection. This research re-addresses the relation between closure and shape memory, focusing on how contour closure affects the ability to learn to recognize novel contour shapes. Of particular interest is whether closed contour shapes are easier to learn to recognize and, if so, whether this benefit is due to better encoding of closed contour shapes or easier comparison of closed contour shapes to already learned shapes. The results show that closed contours are indeed easier to recognize and, further, that this advantage appears to be related to better encoding.

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Effects of object shape on the visual guidance of action

Cited by 4 publications

References 0 publications

Online processing of shape information for control of grasping

Online processing of shape information for control of grasping

Visual information about object size and object position are retained differently in the visual brain: Evidence from grasping studies

The Effect of Contour Closure on Shape Recognition

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