TY - JOUR
T1 - Reaching beyond spatial perception
T2 - Effects of intended furture actions on visually guided prehension
AU - Johnson-Frey, Scott H.
AU - McCarty, Michael E.
AU - Keen, Rachel
PY - 2004/2
Y1 - 2004/2
N2 - Three experiments examined whether manipulating actors' intentions, regarding forthcoming actions, influences the time course and kinematics of visually guided, reach-to-grasp movements. Subjects performed two-step action sequences where the initial movement always involved reaching for and grasping cubes located at a constant distance. Demands of the second movement were systematically manipulated. Although the spatial parameters (cube size and distance) remained constant across all conditions, the durations of the initial movements differed substantially depending on the actions subjects intended to perform once the objects were in hand. Less time was required to engage a small (1 cm3) cube when the intention was to transport it to a new location on the workspace vs. a large (4 cm3) cube when the goal was to merely lift it above its current resting position (Experiment 1). This difference in duration of the initial movement reflects more time spent in the deceleration phase of the reach when the task does not require transporting the cube to a new location on the workspace. Further, this context effect is not related to accuracy demands (Experiment 2), or complexity (Experiment 3) of the intended second movement. These findings demonstrate that actions are determined both by the perceived spatial demands of the immediate movement as well as the intended goal of the entire action sequence.
AB - Three experiments examined whether manipulating actors' intentions, regarding forthcoming actions, influences the time course and kinematics of visually guided, reach-to-grasp movements. Subjects performed two-step action sequences where the initial movement always involved reaching for and grasping cubes located at a constant distance. Demands of the second movement were systematically manipulated. Although the spatial parameters (cube size and distance) remained constant across all conditions, the durations of the initial movements differed substantially depending on the actions subjects intended to perform once the objects were in hand. Less time was required to engage a small (1 cm3) cube when the intention was to transport it to a new location on the workspace vs. a large (4 cm3) cube when the goal was to merely lift it above its current resting position (Experiment 1). This difference in duration of the initial movement reflects more time spent in the deceleration phase of the reach when the task does not require transporting the cube to a new location on the workspace. Further, this context effect is not related to accuracy demands (Experiment 2), or complexity (Experiment 3) of the intended second movement. These findings demonstrate that actions are determined both by the perceived spatial demands of the immediate movement as well as the intended goal of the entire action sequence.
UR - http://www.scopus.com/inward/record.url?scp=1542401912&partnerID=8YFLogxK
U2 - 10.1080/13506280344000329
DO - 10.1080/13506280344000329
M3 - Article
AN - SCOPUS:1542401912
VL - 11
SP - 371
EP - 399
JO - Visual Cognition
JF - Visual Cognition
SN - 1350-6285
IS - 2-3
ER -