Abstract
The purpose of this study was to examine the postural control involved in standing up with support in the context of an
environmental structure. The occasions on which an infant 8-11 months of age stood with support were observed at
his home. The routes followed by his four limbs were analyzed separately in terms of perceived surface layout and
divided into three phases: the first contact with the vertical layout, the trajectory of standing up, and the subsequent
trajectory. The results showed that the infant detected several kinds of vertically organized surface layouts and
discriminated accordingly for each postural change. The data suggested that detection of vertical surface layouts and
their related edges contributed both mechanically and visually to the emergence of standing up with support.
