Key points are not available for this paper at this time.
Karen E. Adolph, Marion A. Eppler, Eleanor J. Gibson, Crawling versus Walking Infants' Perception of Affordances for Locomotion over Sloping Surfaces, Child Development, Vol. 64, No. 4 (Aug., 1993), pp. 1158-1174
Adolph et al. (Sun,) studied this question.