The sensorimotor stage is the first stage of Piaget’s theory. In this stage, babies “think” with their eyes, ear, and hands. Children in this stage learn about the world through their senses. Piaget thought that children in this stage learn by doing the same acts over and over. These acts come from their sense experience. Piaget called this circular reaction. There are two main kinds of circular reaction: primary and secondary. One month olds use primary circular reaction. In primary circular reaction children do acts that have to do with their basic needs, like eating. Four to eight month olds use secondary circular reaction. Secondary circular reaction happens when children try to make events happen with their acts. Secondary circular reaction in children helps to control their own behavior. Eight to twelve month olds can control their behavior. In the sensorimotor stage, children gain object permanence. This happens between 8 and 12 months. Object permanence is knowing that a thing is still in existence even if the child cannot see it. Object permanence is seen in children eight to twelve months old. Object permanence can be seen in Piaget’s object hiding task. In the task a toy is hidden under a blanket. If the baby can find the toy than the baby has learned object permanence.