An investigation of lateral holding biases in pre-school-age children

Most adults hold infants asymmetrically and in the same direction, with the infant's head and upper body to the left of the holder's midline. Although many studies have explored the bias in adults, especially in mothers with their newborn infants, no adequate explanation of the bias has been supported. The current study approaches the question from a developmental standpoint, assessing the earliest manifestation of the bias to determine its origins and covariates, specifically sex and handedness. A community sample of ninety-seven pre-school children, who were tested in their homes, were asked to hold a realistic-looking infant doll on three occasions to assess degree of bias. Three main concerns were addressed. First, prior developmental studies assessed the bias in children from one of three different countries, Sweden, South Africa, and Brazil. The current study extended this work to children from the United States. Second, prior studies came to different conclusions about age of onset: one report first finding the bias in 2-year-olds, another in 4 year olds, and the last in 6-year-olds. The current study therefore sampled children between the ages of 3 and 5 to cover the possible period of transition. It also used improved methods to repeatedly assess the strength of the bias as reflected in the stability of the hold, its closeness and duration, and its flexibility when the child had to perform a concurrent manual task. Using realistic dolls, the results suggested that while the bias is not yet established in the group as a whole, girls but not boys showed repeated, albeit non-significant, preferences to hold on the left. Girls also were significantly more likely to hold the dolls closer to their body and for longer periods of time. Finally, while handedness had no clear association to the bias in and of itself, when there was concurrent manual task, where the child was asked to "feed the baby," left-holders continued to hold on the left while middle- and right-holders switched to the left, presumably to free their dominant hand. In sum, findings provide a preliminary indication that the 3-to-5-year age range is an important transition period for the development of the bias and for the first appearance of sex differences in characteristics of infant holding.