Purpose: Exploring the body-scaled boundary ratios for reach-to-grasp cylinders of hand aperture and the movement time of transport phase, so as to examine the effect of body-scaled information for direct perception perspective on the reach-to-grasp movement. Methods: Sixteen participants (26.3±6.5 years) were recruited. Cylinders (2, 4, 6, 8, 10, and 12 cm in diameter) were used as target objects with counterbalancing for the range sequence. Each object was carried out for 10 trials. Six degrees of freedom Polhemus LIBERTY and MotionMonitor software were used to collect kinematics data. Results: One-way ANOVA with repeated measures revealed that significant difference (p＜.05) for the hand aperture remain distance was found, when participants reaching-to-grasping various size of cylinders. Reach-to-grasp movement was influenced by body-scaled information of diameter-hand and the boundary ratio ranged from 0.34 to 0.51; and significant difference (p＜.05) was also found for transport phase movement time to whole movement time. The transport movement time of reach-to-grasp was influenced by body-scaled information and the boundary ratio ranged from 0.51 to 0.67. Conclusions: Individual picks up the body-scaled information from affordances directly for reach-to-grasp movement, besides body-scaled boundary ratios of hand's parameters, and transport movement time within unique ranges.
- direct perception
- body-scaled information