The continuous development of arm movements in neonates

The development of skilled action such as reaching out to grab a small toy, is usually described as a discrete step in development. Newborn infants are thought to be reflexive organisms, incapable of producing voluntary, goal-directed movements. Under the influence of cortical maturation, the infantile reflexes are thought to gradually disappear, opening the way for intentional reaching and grasping movements at around four months of age. In this paper, we will first present two contrasting theories of development. A series of experiments from our laboratory will then be described showing evidence that the arm movements of newborn babies are both precisely coordinated and under visual control. We will then report additional data showing that sighted neonates are capable of controlling their arms on the basis of auditory information as well. The implications of these findings for the early intervention of babies with a visual handicap will be discussed. An ecological theory will be proposed which stresses the importance of (self-) exploration for setting up a bodily frame of reference and the detection of affordances during development. In such an approach, the development of perception and action go hand in hand in a never-ending circle. Therefore, the development of reaching and grasping is best regarded as a continuous process, starting at or even before birth and culminating in successful reaching.