The development of locomotor planning for end-state comfort.

Walking through real-world environments involves using perceptual information to make complex choices between alternative routes, and this ability must develop through childhood. We examined performance and its development in one such situation. We used a novel 'river-crossing' paradigm analogous to manual 'end-state comfort' planning tasks, where an uncomfortable manoeuvre at the start of a movement is traded off for comfort at its end. Adults showed locomotor end-state comfort planning, adjusting feet at the start of a route in order to gain comfort at its end (crossing a manageable gap between two stepping stones). 3-6-year-olds also made this trade-off, but to a lesser degree than adults. The results suggest that end-state comfort is an important determiner of locomotor behaviour. Furthermore, they show that children as young as 3 years can use detailed visual information to form sophisticated locomotor plans.