What causes scale errors in children?

A recent article by DeLoache et al. has documented an intriguing phenomenon in the development of action planning in young children. When children act on toy replicas of larger objects they make scale errors that are consistent with the full-sized object. Although the actions selected are inappropriate, their execution accurately takes into account the true size of the target. This phenomenon permits tests of the predictions of the perception-action and planning-control models of vision for action.