What is the first postnatal age range when stereopsis (depth perception) typically emerges?

• A. Around 6–9 Months
• B. Around 12–18 Months
• C. Around 3–5 Months
• D. Around 9–12 Months

Answer: (C)

Depth perception from both eyes comes online as the visual system matures enough to fuse images and extract binocular disparity. In healthy infants, this ability to use binocular cues for depth typically appears around three to five months after birth. Before this window, depth perception from disparity isn’t yet robust, though infants can rely on monocular cues such as motion or relative size. By about three to five months, the brain’s binocular pathways are developing, allowing true stereopsis to emerge and then continue to refine with age. If eye alignment is disrupted (for example, by strabismus) or vision is significantly blurred, the onset can be delayed and stereoacuity may be reduced. The later ranges represent ages after stereopsis has typically already appeared.