Abstract
This case study focused on the development of postural dynamics for reaching by an infant from a prone position. This transitional process was examined from a functional perspective. A total of 155 acts of reaching from a prone position were observed on 9 separate days between the ages of 5 and 8 months, and were analyzed from both quantitative and qualitative points of view. First, all acts were classified into three types, based on whether each reaching act had the function of supporting the upper body. The frequency and rate of appearance of each type were analyzed quantitatively for the nine days. Second, coordination of body parts was analyzed qualitatively for each day. The results showed that the infant's reaching changed from having two functions (both touching the object and adjusting the supporting surface) to having only the one function of touching the object. It appeared that an increase in flexibility of coordination of body parts was behind this change. In addition, this study showed that by creating and utilizing instability and in uplifting the upper body and extending the arms, infants may achieve new postural dynamics leading to crawling.
