Final answer:
Between 6 and 12 months, all babies have generally acquired depth perception, which is an essential aspect of visual and spatial development during infancy.
Step-by-step explanation:
Research has determined that between the ages of 6 and 12 months, all babies have acquired depth perception. This cognitive milestone is part of an infant's visual and spatial development. At around six months, a baby's vision has matured nearly to adult levels of acuity, and they begin to discriminate depth.
Babies observe their environments and develop the ability to understand that objects continue to exist even when out of sight (object permanence), a concept grasped by around 8 months old. Additionally, by the end of the first year, most infants can pull up to stand, and some may even start to walk.
In contrast, the abilities to talk and walk fully are generally developed later. Toddlers around the age of 12-24 months master speech development and motor skills, such as walking without support. Complete potty-training abilities are also typically noticed around age three. For example, three-year-olds can speak in simple sentences, learn new words, and become mostly toilet trained.