Babies are interested in the game of “hide and seek” when they reach five or six months of age. If you use a handkerchief to cover your face when you are with your baby, and then suddenly remove the handkerchief and let your face out, the baby will laugh happily. If you do it again and again, the baby will be happy again and again. The fact that the baby likes the game of “hide and seek” indicates that the baby has reached a new level of intellectual development. Before this, as long as he sees something disappear from his field of vision, he thinks that something no longer exists, because the outside world is not yet able to form an image in the infant’s mind; or the image of the outside world exists only when he can see it, and once the object disappears, the image also disappears, just as the image of the object in the mirror disappears with the object. However, when the infant reaches the age of five or six months, the situation is different. The image formed in the infant’s mind by an external object is retained for a very short period of time. At this point, the infant sees something that disappears from view, but the image or representation of the physical object remains in the infant’s mind. Thus, the baby begins to realize that physical objects in the outside world do not cease to exist because he or she cannot see them. Things exist even when they disappear. This is often referred to as “object permanence” in developmental psychology. Infants who are just beginning to recognize object permanence enjoy the game of “hide and seek”. Moreover, a distinctive feature of this game is that when you cover your face with a handkerchief, the child will stare at the place where your face disappears, because he thinks it disappears from here and should be found here. So when you do appear, he looks very excited and smiles happily straight away. If it does not reappear from the place where it just disappeared, but appears somewhere else, the infant is puzzled or surprised. However, as the child’s “object permanence” develops further, this confusion and surprise will disappear. That is when he really understands that objects can exist somewhere else after they disappear from one place. The game of “hide and seek”, on the one hand, allows the child to develop his positive emotions with pleasure and, on the other hand, contributes to the development of the infant’s awareness of “object permanence”, which helps to form representations in the infant’s brain and to develop the imagination.