Final answer:
A mobile should be placed within eight to twenty-four inches of an infant to align with their limited visual capabilities at birth, which is crucial for visual development and stimulation.
Step-by-step explanation:
A mobile should be placed about eight to twenty-four inches from an infant for optimal visual stimulation. The reason for this is that newborns have a limited focal range and are best able to see objects within this distance. At birth, infants' vision is the least developed of their senses, and they are only able to focus on objects that are directly in front of their face at about 18 inches (46 cm) away. This range is perfect for ensuring that they can see their mother's face while feeding, which is vital for bonding and developmental reasons.
As they grow, infants' vision will rapidly improve. By six months, their vision nearly matches that of an adult, which means they can recognize faces at a greater distance, perceive depth, and distinguish colors better. However, in the early weeks, keeping objects like a mobile within the eight to twenty-four-inch range helps to encourage visual development and can provide entertainment and stimulation for the baby.