caa a22 4500 445351810 CHVBK 20180317142846.0 cr unu---uuuuu 170323e20110501xx s 000 0 eng 10.1007/s00221-011-2659-2 doi (NATIONALLICENCE)springer-10.1007/s00221-011-2659-2 Discovering affordances that determine the spatial structure of reach-to-grasp movements [Elektronische Daten] [Mark Mon-Williams, Geoffrey Bingham] Extensive research has identified the affordances used to guide actions, as originally conceived by Gibson (Perceiving, acting, and knowing: towards an ecological psychology. Erlbaum, Hillsdale, 1977; The ecological approach to visual perception. Erlbaum, Hillsdale, 1979/1986). We sought to discover the object affordance properties that determine the spatial structure of reach-to-grasp movements—movements that entail both collision avoidance and targeting. First, we constructed objects that presented a significant collision hazard and varied properties relevant to targeting, namely, object width and size of contact surface. Participants reached-to-grasp objects at three speeds (slow, normal, and fast). In Experiment 1, we explored a "stop” task where participants grasped the objects without moving them. In Experiment 2, we studied "fly-through” movements where the objects were lifted. We discovered the object affordance properties that produced covariance in the spatial structure of reaches-to-grasp. Maximum grasp aperture (MGA) reflected affordances determined by collision avoidance. Terminal grasp aperture (TGA)—when the hand stops moving but prior to finger contact—reflected affordances relevant to targeting accuracy. A model with a single free parameter predicted the prehensile spatial structure and provided a functional affordance-based account of that structure. In Experiment 3, we investigated a "slam” task where participants reached-to-grasp flat rectangular objects on a tabletop. The affordance structure of this task was found to eliminate the collision risk and thus reduced safety margins in MGA and TGA to zero for larger objects. The results emphasize the role of affordances in determining the structure and scaling of reach-to-grasp actions. Finally, we report evidence supporting the opposition vector as an appropriate unit of analysis in the study of grasping and a unit of action that maps directly to affordance properties. Springer-Verlag, 2011 Affordances nationallicence Reach-to-grasp nationallicence Perception/action nationallicence Mathematical model nationallicence Mon-Williams Mark University of Leeds, Leeds, UK aut Bingham Geoffrey Psychological and Brain Sciences, Indiana University, 47405-7007, Bloomington, IN, USA aut Experimental Brain Research Springer-Verlag 211/1(2011-05-01), 145-160 0014-4819 211:1<145 2011 211 221 https://doi.org/10.1007/s00221-011-2659-2 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s00221-011-2659-2 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Mon-Williams Mark University of Leeds, Leeds, UK aut NATIONALLICENCE 700 1- Bingham Geoffrey Psychological and Brain Sciences, Indiana University, 47405-7007, Bloomington, IN, USA aut NATIONALLICENCE 773 0- Experimental Brain Research Springer-Verlag 211/1(2011-05-01), 145-160 0014-4819 211:1<145 2011 211 221 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer