New walkers with Down syndrome use cautious but effective strategies for crossing obstacles.

Perception of affordances research in children with developmental disabilities has only examined well practiced skills. Ten toddlers with Down syndrome and 10 with typical development walked across a GAITRite mat, with and without an obstacle. We coded the toddlers' behaviors after 1 and 3 months of walking experience when they encountered the obstacle (avoid, crawl, error and walk successfully) and calculated gait parameters (step length, width, and velocity). Both groups actively explored their affordances. Despite similar decreases in step length and velocity when approaching the obstacle, toddlers with Down syndrome were more likely to select successful but conservative crawling strategies that minimized balance requirements and reduced risk of falling. Group differences were due to risk management rather than difficulty perceiving affordances.