What are the manifestations of an infant's unconditioned reflexes?

The main unconditioned reflexes in infants include rooting reflex, sucking reflex, grasp reflex, and startle reflex, among others. Their specific manifestations are as follows:

1. Rooting Reflex

When the newborn's cheek or mouth is lightly touched with a nipple or bottle, the infant will turn their head toward the stimulated side and open their mouth to search—that is the rooting reflex.

2. Sucking Reflex

In a calm and awake infant, touching the lips or inserting a finger into the mouth causes the infant to open their mouth and perform sucking movements. This reflex typically disappears at 3–4 months after birth.

3. Grasp Reflex

When the infant is calm and alert, inserting a finger along the ulnar side of the infant’s palm and gently pressing the palm causes the infant to tightly grip the examiner’s finger—this is the grasp reflex.

4. Startle Reflex

Upon hearing a loud noise, the infant may clench their fists, draw their knees up toward the abdomen, or suddenly startle themselves while sound asleep—these reactions belong to the startle reflex.

In addition, other unconditioned reflexes in infants include the Moro reflex (embrace reflex), stepping reflex, and Babinski reflex, among others, each exhibiting distinct characteristics.