Manual Prehension

The animations above show the frontal view, a 3D view, and the bird's eye view of a reaches-to-grasp movement. This process may only take a fraction of a second to complete and yet its underlying dynamics is rather complex and can tell a lot about how the actor perceives the 3D object that s/he is trying to grasp as well as the actor him/herself.

The idea behind studying reaches-to-grasp, along with other visually-guided actions, stemmed from the revolutionary work by James J. Gibson and his ecological approach to visual perception. Traditional psychology theories primarily focus on the organism - how one passively receive various sensory stimulation through sensory organs and piece those low-level stimulation into high-level representations of the world around them. Philosophically, this may lead to solipsism, the idea that the self is all that can be known to exist. Empirically, this may retrain the scope at which psychologists investigate human perception. Instead, Gibson proposed that the organism and its surrounding are inseparable and that the organism is always "environed" by the physical world around it. Perception, in this regard, is merely "picking up" the information that specifies the relationship between the organism and its surrounding, a process that does not require mental reconstruction of the world, as the world is already out there and exists. Studying reaches-to-grasping will help to elucidate this constantly evolving relationship between human observers and the object that they interact with.

Related Publications

Herth, R.A., Wang, X.M., Cherry, O.C., & Bingham, G.P. (under review). Monocular guidance of reaches-to-grasp using visible support surface texture: Data and model. Experimental Brain Research.

Wang, X.M., & Bingham, G.P. (2019). Change in effectivity yields recalibration of affordance geometry to preserve functional dynamics. Experimental Brain Research, 237(3), 817-827.