Looking away before moving forward: changes in optic-flow perception precede locomotor development.

Voluntary locomotion is one of the most important motor actions performed by animals, including humans, and vision plays an important role in controlling such action. We conducted cross-sectional (Experiment 1) and longitudinal (Experiment 2) investigations and found that the perception of visual motion (optic flow), a critical cue for perceiving and controlling the direction of locomotion, drastically changes just before the emergence of locomotion in infancy. The results suggest that developmental change in particular visual perceptions precedes and potentially promotes the emergence of related motor actions in early development. Our findings offer a new perspective on the development of visuomotor coordination, which has long been thought to derive from the development of motor actions rather than from changes in visual perceptions.