During the first year or so of the child's life, his playful activity takes shape in several ways. First, out of the great variety of the random movements certain ones are picked out and fixed. This is the way with putting the hand into the mouth or drumming on the floor with the heels, and these instances illustrate the important fact that many learned acts develop out of the child's random activity. Without play activity there would be little work or accomplishment of the distinctively human type. Second, certain specific movements, those of locomotion and vocalization, appear with the ripening of the child's native equipment, and take an important place in his play. Third, his play comes to consist more and more of responses to external objects, instead of to internal stimuli as at first. The playful responses to external objects fall into two classes, according as they manipulate objects or simply examine them. We have, then, a small group of instincts that is very closely related to the fundamental instinct of random activity. Locomotion. Evidence has already been presented [Footnote: See p. 95.] indicating that walking is instinctive and not learned, so that the human species is no exception to the rule that every species has its instinctive mode of locomotion. Simpler performances which enter into the very complex movement of walking make their appearance separately in the infant before being combined into walking proper. Holding up the head, sitting up, kicking with an alternate motion of the {153} two legs, and creeping, ordinarily precede walking and lead up to it. What is the natural stimulus to locomotion? It is as difficult to say as it is to specify the stimulus in other forms of playful activity. From the fact that blind children are usually delayed in beginning to walk, we judge that the sense of sight furnishes some of the most effective stimuli to this response. Often the impulse attending locomotion is the impulse to approach some seen object, but probably some satisfaction is derived simply from the free movement itself. There certainly is no special emotion going with locomotion. Locomotion has, of course, plenty of "survival value", and might have been included among the organic instincts.