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Vivian C. Paulun, Karl R. Gegenfurtner, Melvyn A. Goodale, Roland W. Fleming; Getting a grip on different materials. Journal of Vision 2014;14(10):903. doi: https://doi.org/10.1167/14.10.903.
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© ARVO (1962-2015); The Authors (2016-present)
A precision grip of index finger and thumb is often used to interact with objects in our environment. To successfully accomplish this everyday task we adapt our grip depending on various extrinsic and intrinsic properties of the object to be grasped. For example, the grasping movement needs to be adjusted if we want to grasp a wooden spoon or a wet bar of soap to provide a stable grip without the object rotating or falling. This adjustment not only depends on object features like shape or size, but presumably also on the visually perceived material the object is made of. We let our participants grasp cylinders of the same size (height: 10 cm, diameter: 2.5 cm) but different materials, i.e. foam, wood and brass as well as an additional brass cylinder covered with vaseline to make it slippery. These stimuli laid on their long side at six different angles with respect to the participants (0°, i.e. horizontally, 30°, 60°, 90°, 120°, 150° rotated counterclockwise). The task was to grasp, lift and carry the target objects to a goal position and place them there. We found that timing of the movement towards and while holding the cylinders was influenced by its material properties. Reaction time, movement duration to the object, handling and transport duration were on average longer for the slippery cylinder covered with vaseline. Object orientation appeared to primarily affect spatial characteristics of the movement like position and orientation of the grasp axis. However, these spatial effects were modulated by the material of the target object. Taken together our results imply that the timing and positioning of the precision grip depends on the object's visually perceived material properties.
Meeting abstract presented at VSS 2014
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