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To Move or to Use: Task Goals Drive Kinematic Differences in Object-Directed Action

Poster Session D - Monday, March 9, 2026, 8:00 – 10:00 am PDT, Fairview/Kitsilano Ballroom

Anna M. Keresztesy¹ (), Marshall Kim¹, Jessica M. Smith², Hugo Angulo², Bradford Z. Mahon^1-3, Frank E. Garcea^1,4-6; ¹Department of Neurosurgery, University of Rochester Medical Center, USA, ²Department of Psychology, Carnegie Mellon University, USA, ³Neuroscience Institute, Carnegie Mellon University, USA, ⁴Department of Neuroscience, University of Rochester, USA, ⁵Department of Brain and Cognitive Sciences, University of Rochester, USA, ⁶Del Monte Institute for Neuroscience, University of Rochester Medical Center, USA

Motor planning is a fundamental cognitive function providing flexibility to manipulate objects according to task goals. For example, when moving a spoon into a cabinet, numerous parts of the object can be grasped. But when the goal is to eat soup with a spoon, the object must be grasped in a manner that anticipates its subsequent use. Here, we developed a markerless hand posture tracking system using the OpenCV and MediaPipe libraries to measure speed when initiating and executing movements, and grip aperture precision (distance between thumb and index finger) as 16 neurotypical participants grasped objects and placed them into a nearby container directly, or after performing use actions. Half of the participants completed 4 blocks of grasp-to-move trials, followed by 4 blocks of grasp-to-use trials (and vice versa for the other half). Participants wore occlusion glasses to block visual processing and prevent motor planning before an auditory cue was presented, at which point the lenses became transparent and participants executed the action. This allowed us to test how task goals modulate action kinematic features while holding stimuli constant. We tested two hypotheses: (H1) Grasping-to-use actions require more precise grip aperture than grasping-to-move; and (H2) Grasping-to-use actions are performed more slowly than grasping-to-move actions. Analyses comparing differences in these variables as a function of task goals support both hypotheses. Our findings indicate that motor planning processes modulate kinematic features of grasping actions, and demonstrate the feasibility of markerless hand posture tracking as a tool to study cognitive processing.

Topic Area: PERCEPTION & ACTION: Motor control