How wierd is this- I was looking at a review paper  of the development of visual acuity in human infants and I plotted the average acuity measurements for the first three years of life. It’s a straight line. A very straight line.
Not only is it testament to the experimental rigour of the studies included in the review but it’s also pretty developmentally odd- I mean what else develops linearly? Height doesn’t. Vocabularly use doesn’t. Number conservation doesn’t.
Does anything else develop linearly? There must be so many non-linear processes involved in the neural development of vision it’s a marvel it comes out linear with respect to age.
 Courage, M.L., and Adams, R.J. (1990). Visual acuity assessment from birth to three years using the acuity card procedure: Cross-sectional and longitudinal samples. Ophthalmic and Physiological Optics, 67(9), 713-718.
Acuity was measured with black and white gratings of different spatial frequencies and is shown here in cpd, cycles per degree of visual angle (this is an inverse function of the Snellen rating (eg 20/20).