REFLEXES

 REFLEXES

The newborn is not completely helpless. Among other things, it has some basic reflexes. For example, the newborn automatically holds its breath and contracts its throat to keep water out. Reflexes are built-in reactions to stimuli; they govern the newborn’s movements, which are automatic and beyond the newborn’s control. Reflexes are genetically carried survival mechanisms. They allow infants to respond adaptively to their environment before they have had an opportunity to learn.  

The rooting and sucking reflexes are important examples. Both have survival value for newborn mammals, who must find a mother’s breast to obtain nourishment.

The rooting reflex occurs when the infant’s cheek is stroked or the side of the mouth is touched. In response, the infant turns its head toward the side that was touched in an apparent effort to find something to suck. The sucking reflex occurs when newborns automatically suck an object placed in their mouth. This reflex enables newborns to get nourishment before they have associated a nipple with food; sucking also serves as a self-soothing or self-regulating mechanism.

Another example is the Moro reflex , which occurs in response to a sudden, intense noise or movement. When startled, the newborn arches its back, throws back its head, and flings out its arms and legs. Then the newborn rapidly closes its arms and legs. The Moro reflex is believed to be a way of grabbing for support while falling; it would have had survival value for our primate ancestors.

Some reflexes—coughing, sneezing, blinking, shivering, and yawning, for example—persist throughout life. They are as important for the adult as they are for the infant. Other reflexes, though, disappear several months following birth, as the infant’s brain matures, and voluntary control over many behaviors develops. The rooting and Moro reflexes, for example, tend to disappear when the infant is 3 to 4 months old.

The movements of some reflexes eventually become incorporated into more complex, voluntary actions. One important example is the grasping reflex , which occurs when something touches the infant’s palms. The infant responds by grasping tightly.  By the end of the third month, the grasping reflex diminishes, and the infant shows a more voluntary grasp. As its motor development becomes smoother, the infant will grasp objects, carefully manipulate them, and explore their qualities. An overview of the reflexes we have discussed, along with others, is given in Figure 5.1.  Although reflexes are automatic and inborn, differences in reflexive behavior are soon apparent. For example, the sucking capabilities of newborns vary considerably. Some newborns are efficient at forcefully sucking and obtaining milk; others are not as adept and get tired before they are full. Most infants take several weeks to establish a sucking style that is coordinated with the way the mother is holding the infant, the way milk is coming out of the bottle or breast, and the infant’s temperament.

reflexes Built-in reactions to stimuli.

rooting reflex A newborn’s built-in reaction that occurs when the infant’s cheek is stroked or the side of the mouth is touched. In response, the infant turns its head toward the side that was touched, in an apparent effort to find something to suck.

sucking reflex A newborn’s built-in reaction of automatically sucking an object placed in its mouth. The sucking reflex enables the infant to get nourishment before it has associated a nipple with food.

Moro reflex A neonatal startle response that occurs in reaction to a sudden, intense noise or movement. When startled, the newborn arches its back, throws its head back, and flings out its arms and legs. Then the newborn rapidly closes its arms and legs to the center of the body.

grasping reflex A neonatal reflex that occurs when something touches the infant’s palms. The infant responds by grasping tightly.

gross motor skills Motor skills that involve large muscle activities, such as moving one’s arms and walking.