Infancy is the period of development between birth and the onset of language, which covers approximately the first 18 months of life. Systematic study of infants began in the nineteenth century. One of the earliest scientific studies was by Charles Darwin, who kept a diary of the development of his infant son William during the year 1844. One of the major scientific achievements since the mid-1960s has been radically to revise this nineteenth-century preconception in favour of an image of the infant as “competent” and well adapted to the demands of the physical and social environment. Gesell considered that the infant’s motor development, from gaining of early head control to crawling and walking, unfolded on a rather inevitable biological timetable of “motor milestones”. The modern era of infancy research was inaugurated by Jean Piaget. Perception has a particularly important part to play in the acquisition of skills in infancy.