LEARNING TO CRAWL

The effects of infants' age, body dimensions, and experience on the de velopment of crawling was examined by observing 28 infants longitudina lly, from children's first attempts at crawling until they began walki ng. Although most infants displayed multiple crawling postures en rout e to walking, development did not adhere to a strict progression of ob ligatory, discrete stages. In particular, 15 infants crawled on their bellies prior to crawling on hands and knees, but the other 13 infants skipped the belly-crawling period and proceeded directly to crawling on hands and knees. Duration of experience with earlier forms of crawl ing predicted the speed and efficiency of later, quite different forms of crawling. Most important, infants who had formerly belly crawled w ere more proficient crawling on hands and knees than infants who had s kipped the belly-crawling period. Transfer could not be explained by d ifferences in infants' age or body dimensions alone. Rather, experienc e using earlier crawling patterns may have exerted beneficial effects on hands-and-knees crawling by shoring up underlying constituents comm on to all forms of crawling postures.