Touch

Touch in Newborns and Infants

Mouthing and oral exploration provide fundamental means for infants to interact with objects. However, the hands often help with these interactions mainly thanks to the hand-mouth coordination that exists from birth and even before, in utero. Young infants display hand reflex reactions, such as grasping and avoiding. Beyond these reflexes, they are able to hold small objects and detect differences in their contours. Researchers used a habituation/dishabituation procedure without visual inspection to reveal this haptic ability. Habituation involves putting a small object in the newborn’s hand. The newborn holds the object for a time and then drops it. The object is placed several times in the newborn’s hand until a decrease in holding time occurs. The decrease in holding time reveals the infant’s abilities to perceive, memorize, and recognize the shape. Then, a novel object is placed in the same hand and if the holding time increases, it is concluded that the newborn discriminated between the object shapes. This ability is already present in newborns and even in 33-week postconceptional preterm infants. This ability is obtained with both the right and left hands. In addition to shape discrimination, newborns also discriminate texture, such as smooth versus rough. Intermanual transfer of shape and texture, namely, a recognition of the familiar object in the opposite hand, is also possible at this young age.

Within the first 6 months after birth, young babies are capable of good performance in detecting other shape characteristics. Nevertheless, this performance does not allow one to conclude that they have a clear representation of what they hold in their hand because their manual exploration is often insufficient. Grasping with repetitive squeezing and releasing of the objects is observed, and infants are unable to perform the integration of pieces of information stored in their working memory. In 4- to 5-month-old infants, bimanual coordination is possible. They can actively explore two ends of a haptic display with one end in each hand. They perceive the ends as one connected unit when their movements undergo a common rigid motion and as two distinct units when their movements undergo independent motion.

...