Piaget's Sensorimotor Stage is the stage of
cognitive development exhibited between birth through the early second year.
It is during this stage that children experience everything through sensory and motor interaction. A child's entire world is grasped only through the venues of hearing, looking, mouthing, grasping and touching. During the first six months of this stage, a child lacks what Piaget refers to as object permanence. In short, if an object is out of sight, it is also out of mind. When a child grows beyond six months of age, he or she begins to gain awareness that objects exist beyond direct perception. This cognition is at first only instant, but later in development becomes more residual and the infant will look for something even if some time has passed between the last impression of that object and when he or she is allowed to look for that object.
It has since been proven that object permanence exists to some degree in children as young as a month old. It remains, however, a valid attempt to classify the development psychology of infants in this age range.