End-state comfort in two object manipulation tasks: Investigating how the movement context influences planning in...

The movement context (pantomime, pantomime with image/object as guide, and actual use) has been shown to influence end-state comfort-the propensity to prioritize a comfortable final hand position over an initially comfortable one-across the lifespan. The present study aimed to assess how the movement context (pantomime, using a dowel as the tool, and actual use) influences end-state comfort when acting with objects (glass/hammer) that differ in use-dependent experience. Children (ages 6-11, n = 70), young adults (n = 21), and older adults (n = 21) picked up an overturned glass to pour water and a hammer to hit a nail, where the handle faced away from the participant. End-state comfort was assessed in each movement context. Findings provide support for an increase in end-state comfort with age, adult-like patterns at age 10, and no difference between older adults and 8- to 9-year-old children. In addition, this work revealed that perception of "graspability" led to an increase in end-state comfort in the hammering task; therefore, suggesting our ability to act with objects and tools in the environment is influenced by use-dependent experience and object perception. Results add to our understanding of changes in motor planning abilities with age, and factors underlying these changes.