Human infants' ability to perceive touch in external space develops postnatally.

Arriving in the outside world, the newborn infant has to determine how the tactile stimulation experienced in utero relates to the spatial environment newly offered up by vision, hearing and olfaction. We investigated this developmental process by tracing the origins of the influence of external spatial representation on young infants' orienting responses to tactile stimuli. When adults cross their hands or feet they typically make more tactile localization errors than otherwise, and this has been attributed to the conflicts between skin-based and external frames of reference and/or the usual and current locations of touches in external space [1,2]. Here, we report that a group of six-month-olds, like adults, showed a tactile localisation deficit with their feet crossed, indicating external spatial coding of touch; in striking contrast, four-month-olds outperformed the older infants showing no crossed-feet deficit. Thus, in the first months of life, infants perceive touches solipsistically, and only come to locate them in the external world after significant postnatal experience.