A 4-year-old child has received approximately 10^15 bytes of sensory input through the visual cortex, based on an estimate of 20 MB per second from the optical nerve.
a 4-year-old has been awake for 16,000 hours in his or her life, and the amount of information that has reached the visual cortex of that child in four years is about 10 to 15 bytes. And you can compute this by estimating that the optical nerve carry about 20 megabytes per second, roughly.