Innate Behavior in Infants

While many of an infant’s initial behaviors are instinctual and not learned, certain of these automatic reflexes disappear within the first few months of life. points out that much of what an infant does in those first weeks and months after birth is due to automatic responses 1. Although some of these innate reflexes go away in time, others eventually become part of an infant’s voluntary behavior.


Crying is an innate behavior of infants. An infant doesn’t learn how to cry, he just does it. Infants cry for a lot of different reasons as a means of communicating. Babies cry when they’re hungry, sleepy, need changing or are otherwise uncomfortable. They cry when they aren’t feeling well, are over- or under-stimulated or just plain lonely and want to be held close. says that it won’t hurt your baby if you have to let him cry a bit once you’ve seen to his needs 2.


Sucking is an automatic reflex to a newborn. Sometimes the reflex is present even before birth as infants often suck their thumbs while still in the womb. In her book, “The Ecological Standards of Breastfeeding,” La Leche League leader Sheila Kippley points outs that sucking is one of an infant’s most common innate behaviors. After birth, infants rely on the sucking reflex for both nourishment and comfort. Sucking on their fingers or a fist is a natural response that most infants use to soothe themselves.

Grasp Reflexes

A reflex is an automatic, involuntary action, usually in response to a certain stimulus. For example, an infant will grip your finger when you stroke the palm of her hand or she will curl her toes when you stroke the bottom of her foot. While an infant’s grasp in those first weeks of life may feel strong, it’s only a reflex she can’t control. This grasp reflex is an innate behavior that normally decreases during the second month and is absent by the time an infant is 3 months old. At 4 months, a baby begins to grasp objects voluntarily. As she grows, she gains more control over her movements so that her grasping becomes more voluntary.

Response to Stimuli

Infants produce automatic reflexes in response to stimuli in their environments. For example, newborns are sensitive to light and will automatically shut their eyes to glare. An infant usually awakens to touch and will instinctively start to suck if you lightly stroke the corner of her mouth. Although newborns respond to their mothers’ voices from the first day, loud and sudden noises will startle them. The Moro, or startle, reflex, is an involuntary response normally present at birth. Infants react when startled by throwing their arms out to the side. The Moro usually disappears by the time an infant is 6 months old.

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