Babies' brains don't work quite the same as adults. There is so much going on in this new world that their brains can become completely overwhelmed. High contrast shapes and patterns provide the baby with something simple and engaging to focus on, and in this focus – or intense concentration – they can allow their minds to rest. High contrast shapes may appear odd or even a little boring to adults, but they are designed to hold babies' attention and the results from them is breathtaking.
Researchers have repeatedly shown that newborns prefer to look at black and white geometric shapes, rather than bright colors or pastels.
In the early 1960's, Dr. Robert Fantz, a developmental psychologist at Case Western Reserve University in Cleveland, Ohio, who believed that babies under two years of age could see well, designed a "peep box" that surrounded a baby sitting in an infant seat. He placed two objects directly in the baby's view: a patterned black and white checkerboard and a plain gray card. Undetected, Dr. Fantz watched the baby through a little peephole and was able to determine that babies preferred the checkerboard to the non-patterned surface. Their eyes traveled consistently to the checkerboard.
Source: Fantz, R. "Maturation of Pattern Vision in Young Infants." Journal of Comparative and Physiological Psychology, Vol. 55 (1962), p. 907.