Rise of Fascism. As the United States turned inwards to deal with the lingering effects of the Depression, militaristic regimes came to power in Germany, Italy, and Japan promising economic relief and national expansion.
Human faces are one of an infant's favorite and fascinating things to observe, especially when it's mom or dad or his own image staring back at him in a mirror. By 3-months-old, most babies know the difference between familiar faces and strange ones.
Understanding unique things. When a baby is of age lesser than six months, repeated things occur to him as the same things. After the age of six months, the baby starts understanding the same thing occurring again and again is different.