Abstract
How far in advance do humans use visual information to guide locomotion? Paths through everyday environments can commonly include a series of obstacles. Here, by measuring whether the first obstacle in a series is approached differently to a single obstacle, we determine how far in advance the distant obstacles influence locomotion. By comparing children and adults we also ask how this planning develops with age. Fifteen 6-8 year-olds and fifteen adults took part. On each trial the participant walked a path with one, two or three obstacles (separate conditions, presented in random order). Locomotor behaviour was recorded with a 16-camera Vicon motion capture system. Cognitive planning was indexed by performance on a Tower of Hanoi task. When an obstacle was the first in a series, adults crossed it with a shorter trail foot step length and a smaller toe clearance than a single obstacle. Children likewise shortened step length. However, in contrast with adults, they did not modify clearance, but did adjust lead foot step length. A measure of motor planning, calculated as the difference between single and double toe clearances, was not correlated with cognitive planning (Tower of Hanoi performance) at any age. We provide naturalistic evidence in support of recent models (Mattis & Fajen, 2014) which propose that adults make visually- guided adjustments 1-2 steps in advance of obstacle crossing. 6-8-year-old children also make adjustments at this distance or slightly before, but alter different aspects of gait, demonstrating relatively late development in visually-guided locomotion. The results also suggest the independence of cognitive and motor planning abilities at all ages.
Meeting abstract presented at VSS 2016