Description
- Abstract:
- This thesis project addresses the problem of how 3D information is processed for the planning and execution of grasping movements. It aims to test two major hypotheses. First, 3D vision for perception and 3D vision for action are in fact an identity. Second, and corollary of the first hypothesis, 3D vision for action is not veridical: at planning, the 3D properties of the shape of an object are encoded in a non-Euclidean fashion, yielding specific systematic idiosyncrasies during motor execution. Throughout the entire study, grasping tasks are constantly compared with perceptual tasks using within-subject designs. The investigation proceeds incrementally: grasping is first studied in VR, only binocular information is manipulated and no online feedback of the hand is provided; second, vision of the hand, touch, and monocular depth cues are then added to the scene, still using VR; third, a final experiment tests the main findings of the previous studies in a natural environment, using real objects and allowing continuous vision of the actual hand and limb. The findings successfully support the two initial hypotheses: first, the kinematics of the grasping movements show patterns of effects that are remarkably similar to those characterizing perceptual judgments; second, these common effects highlight the presence of systematic biases affecting the processing of 3D information, which have then repercussions on both perception and action, even when multiple cues-to-depth are present and even when online control is available; third, these mechanisms appear to be genuinely intrinsic to the visuomotor system, because subjects' performances do not improve when switching from VR to a natural setting. To partially overcome these biases, the visuomotor system has developed trial-by-trial strategies that help compensating for the errors at planning. In particular, actors tend to adjust their in-flight grip aperture during a given trial, based on the error registered in the previous trial.
- Notes:
- Thesis (Ph. D.)--Brown University, 2017
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Citation
Campagnoli, Carlo,
"Perceiving and grasping in 3D share the same visual mechanisms"
(2017).
Cognitive, Linguistic, and Psychological Sciences Theses and Dissertations.
Brown Digital Repository. Brown University Library.
https://doi.org/10.7301/Z0416VGJ
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Cognitive, Linguistic, and Psychological Sciences Theses and Dissertations
Theses and Dissertations for the Cognitive, Linguistic, and Psychological Sciences department....