Underpinned by the ecological approach to perceptual-motor development, this Thesis aims to contribute to the understanding of the organization of infants’ behaviour during encounters with drop-offs and water environments. Previous studies have linked locomotor experience to infants’ avoidance of falling from heights. Using the Real Cliff / Water Cliff apparatus, Burnay and Cordovil (2016) confirmed the effect of locomotor experience on crawlers’ avoidance of drop-offs and linked locomotor experience to infants’ avoidance of falling into the water for the first time. However, the effect of other specific locomotor experiences on infants’ approach to aquatic environments has not been addressed. This Thesis investigated the effect of specific locomotor experiences and the transition from skilled crawling to novice walking on infants’ behaviour when they encounter real cliffs and two different ways to access the water:​ a cliff and a slope.

Using a cross-sectional design, Study One examined the effect of specific locomotor experiences on 102 infants’ (58 crawlers, 44 walkers) avoidance of falling from a real and a water cliff (tank of water attached to the edge of a drop-off). Crawling and total self-produced locomotor experiences were associated with crawling and walking infants’ behaviour. No association between walking experience and walking infants’ avoidance behaviour was found. Study Two examined 25 infants’ behaviour on the real and the water cliff in a longitudinal design. Infants were tested as experienced crawlers, new walkers and again as experienced walkers. The majority of infants avoided equally or more consistently when tested as new walkers than as experienced crawlers and even more consistently when tested as experienced walkers. Combining results from Study One and Two indicates that some degree of what infants learn through crawling experience about navigating drop-offs transfers to a new walking locomotor pattern. For new walkers, adaptive behaviour requires a recalibration process, and a longer duration of crawling experience facilitates this process.

To investigate if perceptual-motor development influences infants’ avoidance of submersion when a sloped entrance to the water is offered in the same way it does when a drop-off is presented, Study Three examined 77 infants’ (43 crawlers, 34 walkers) avoidance of submersion on a 10⁰ sloped surface leading to deep water. No association between infants’ avoidance of submersion and locomotor experiences was found. Comparison with the results of Study One revealed that the proportion of infants that reached submersion on the slope was greater than the proportion of infants that fell into the water cliff. With self-produced locomotor experience, infants become attuned to relevant perceptual information about threats posed by cliffs (filled with water or not) but locomotor experience does not teach them to perceive water as unsafe when it can be approached via a sloped pathway.

Outcomes of this Thesis can be applied to educate caregivers about sensitive periods when infants are more susceptible to engage in behaviour that heightens drowning risk and to inform them about the potential increased drowning risk posed by swimming pools with sloping access.