Around 4 months of age infants develop the process by which the visual cortex combines differing neural signals, resulting in depth perception. on average, infants 7 months of age become sensitive to depth cues, which can be perceived by one eye alone.

stereopsis; monocular

Around 4 months of age infants develop stereopsis, the process by which the visual cortex combines differing neural signals, resulting in depth perception. On average, infants 7 months of age become sensitive to monocular depth cues, which can be perceived by one eye alone.

In around 4 months, and infant develops what is known as stereopsis. Stereopsis is pretty much the vision that people see with their eyes. What this means is when someone looks at something with both of their eyes, their eyes have a different angle to it, but the signals go  back to the brain and combine the different angles into one perception. Infants would start using stereopsis when they're using their vision.

Monocular depth cues is the information when you're looking at something with one eye. This occurs when someone closes one of their eyes and use the other way to see. This gives an "in depth" view in the brain for "one side"o of a perception. This is especially used when looking at things like a microscope and etc. Infants would feel sensitive with monocular depth cues they would be used to steopsis, in other words, they would be use to using both of their eyes.