Related Experiment Video
Updated: Jul 31, 2026
Methods to Explore the Influence of Top-down Visual Processes on Motor Behavior
Published on: April 16, 2014
Time course analysis of closed- and open-loop grasping of the Müller-Lyer illusion
M Heath1, C Rival, D A Westwood
1Department of Kinesiology and Program in Neural Science, Indiana University, Bloomington, IN 47405, USA. heathm@indiana.edu
Abstract:
The authors investigated whether the early or later stages of closed-loop (CL) and open-loop (OL) grasping movements were differentially influenced by the Müller-Lyer (ML) illusion. Participants (N = 21) reached out and grasped small (5 cm) and large (7 cm) objects embedded within fins-in and fins-out ML configurations. Grasping time (GT) was normalized, and absolute grip aperture (GA) as well as scaled illusion effects were computed at 20%, 40%, 60%, and 80% of GT. The results indicated that CL trials were refractory to the illusory array (i.e., from 20% to 80% of GT), whereas OL trials were influenced by the ML figure during that same time. Those findings suggest that CL trials were supported by unitary and metrical visual information, whereas OL trials were entirely supported by perception-based visual information.
