Final answer:
In response to a loud noise, infants display the Moro reflex, characterized by arm movements and usually crying, which may help them cling to a caregiver for safety.
Step-by-step explanation:
When adults are surprised by a loud noise, they often show the startle reflex. In infants, the same reflex is called the Moro reflex. This reflex involves the infant spreading out the arms, bringing them back in toward the body, and usually crying in response to a sudden loss of support or sensation of falling. This instinctive behavior is present from birth until about three or four months of age and plays a role in an infant's survival, as the motions may help the baby reach out and grab its mother or another caregiver. Other reflexes like the grasping reflex and the sucking reflex also play critical roles in early infancy, aiding in feeding and maintaining close physical contact with the caregiver.