"Where did Nicholas go?" wonders Marco.
A simple game of peek a boo is filled with learning for infants. In the first few months of life an infant is concered with what is before his eyes. As soon as something or someone
of eyesight he forgets about it. Gradually that changes and the infant's world begins to expand beyond his senses. He begins to imagine people and objects even when they are not present-object permanence.
This is a key development in intellectual growth and emotional development.
"As soon as a baby is able of conjuring an image of a person or object in his mind, he is also capable of cognitive thought; remembering, imagining, deductive reasoning and planning."
When an infant develops object permanence he can recall images and take actions based on his recollections.