Learning to move from one place to another is a major milestone in infants’ development. First crawling and later walking, infants start to discover and explore the world around them from a new and independent perspective. Now they are able to crawl or walk to reach a desired toy without relying on help. Crawling and walking infants spend about half of their time during the day moving around, but most of the time that infants could move around, they do not (Adolph, 2002). Instead, they also spend time exploring and manipulating objects and watching others do the same. From early on, infants show a distinct preference for objects in motion. They enjoy watching the mobile moving above the crib, and enjoy even more moving the mobile by kicking it. The cat sneaking around or the dog running across the backyard catches their attention and often makes them squeal with glee. Long before infants are actually able to move on their own, they are attentive observers of motion in general and movements performed by others in particular.

Previous research in the area of motor development has focused on the question of when and how infants learn to crawl and walk (Adolph, 2008), while another branch of research has focused on how infants perceive motion (Bertenthal et al., 1984). It has been demonstrated that before six months of age infants discriminate between walking point-light displays (PLDs) and randomly moving dots (Bertenthal et al., 1984, 1987), indicating an early understanding of movements performed by others. Beyond that, it has been suggested that infants are born with a preference for biological motion (Simion et al., 2008). But, the question of whether perception and production of crawling and walking movements are interlinked has been neglected in infant research so far. This is surprising given the fact that a link between the onset of self-locomotion and developmental changes in perception and cognition has been suggested for decades (Gibson, 1988; Piaget, 1953; for a review, see Campos et al., 2000). This notion is further supported by recent research demonstrating that the ability to crawl enhances 9-month-old infants’ flexibility in memory retrieval (Herbert et al., 2007). The onset of crawling and walking also seems to correspond with major advances in social development as indicated by changes in social looking behaviour in relation to motor skills (Clearfield, 2011). In addition, infants need stimulating physical surroundings and warm care-giving to promote active exploration of the environment and proper attainment of developmental motor milestones (Bendersky and Lewis, 1994). But, the questions of how the perception and production of crawling and walking movements are linked to each other and how they influence each other remain open.