Development of postural reactions and object manipulation in primate infants:

Interconnection between postures and manual actions.

Hideko Takeshita

University of Shiga Prefecture, Japan

Postural control is definitely a limiting factor in action development." (von Hofsten, 1992). This view is important when we compare behavioral development among primate infants, which are born, as postural control is undeveloped. Primate species share various characteristics of postural development, which can be compared with each other. We applied a test of postural development to primate infants consisting of five species of macaques, chimpanzees, orangutans and humans (Takeshita, Tanaka, & Matsuzawa, 1989). The test consisted of 11 sorts of techniques, each of which induced certain postural reactions (Vojta, 1976). Longitudinal observation showed that these induced postural reactions had a common developmental process across the primate species. Such reactions developed in four stages during the first 2 to 3 months in the macaque infants, the first 11 to 12 months in the apes and humans. Although spontaneous postures and locomotions in infants are different among the primate species, induced postural reactions have common characteristics, which provide a useful scale for the cross-species comparison of postnatal behavioral development. We compared the development of object manipulation among species in reference to the developmental stages of postural reactions. Reaching movements appear in the second stage, while increased dexterity and a variety of manipulations is marked in the third stage in all of the species. However, complexity of manipulation in human infants always exceeds that of the other primates. I speculate such superiority of manual actions in human infants is related to their early development in supine patterns and sitting patterns of postural control, in which the limbs are relatively free from supporting the body weight (Takeshita, 1999). The possible implications on the development of 'static' postures in human infants are further discussed in relation to their development of technical intelligence, social intelligence, and interconnection among them.

von Hofsten, C. (1992). Development of manual actions from perceptual perspective. In H. Forssberg & H. Hirshfeld (Eds.), Movement disorders in children. Basel: Karger.

Takeshita, H., Tanaka, M., & Matsuzawa, T. (1989). Development of postural reactions and object manipulation in primate infants. Primate Research [in Japanese with English abstract], 5, 111-120.

Takeshita, H. (1999). Early development of the human mind and language: Comparative study of behavioral development in primates. Tokyo, University of Tokyo Press.

Vojta, V. (1976). Die cerebralen Bewegungsstorungen im Sauglingsalter, Fruhdiagnose, und Fruhtherapie. Stuttgart: Ferdinand Enke Verlag.

Takeshita, Hideko

School of Human Cultures, University of Shiga Prefecture

2500 Hassaka-cho, Hikone, Shiga 522-8533, Japan

takeshit@shc.usp.ac.jp