What is the reflex called when stroking a hungry infant's lips causes the infant to start sucking?

The reflex you're inquiring about is known as the sucking reflex. This reflex is an essential part of an infant's feeding behavior and is initiated when something touches the baby's lips, prompting them to instinctively suck. This action is crucial for feeding, as it allows the infant to obtain nourishment effectively by drawing milk from a breast or bottle.

While the sucking reflex plays a significant role in feeding, the rooting reflex — which is also a critical part of infant survival — occurs when an infant's cheek or lips are stroked, causing the baby to turn their head and open their mouth in search of a nipple. Although related, the rooting reflex is distinct from the sucking reflex.

The grasping reflex and the palmar reflex involve different actions, such as gripping or grasping objects placed in the hands of an infant, and are not directly connected to feeding behavior. Understanding the distinct roles of these reflexes is important for recognizing normal infant development and feeding practices.