Long before the thirtieth week, healthy children distinguish human faces definitely from one another; first, the faces of the mother and the nurse, then the face of the father, seen less often; and all three of these from every strange face. Probably faces are the first thing frequently perceived clearly by the eye. It has been found surprising that infants so much earlier recognize human faces and forms, and follow them with the gaze, than they do other objects. But human forms and faces, being large, moving objects, awaken interest more than other objects do; and on account of the manner of their movements, and because they are the source from which the voice issues, are essentially different from other objects in the field of vision. "In these movements they are also characterized as a coherent whole, and the face, as a whitish-reddish patch with the two sparkling eyes, is always a part of this image that will be easy to recognize, even for one who has seen it but a few times" (Helmholtz). Hence the memory for faces is established earlier than that for other visual impressions, and with this the ability to recognize members of the family. A little girl, who does not speak at all, looks at pictures with considerable interest in the seventh month, "and points meantime with her little forefinger to the heads of the human figures" (Frau von Struempell). My child in the second month could already localize the face and voice of his mother, but the so-called knowing ("Erkennen") is a recognition (Wiedererkennen) which presupposes a very firm _association of the memory-images_. This fundamental function attached to the memory can have but a slow development, because it demands an accumulation of memory-images and precision in them. In the second three months it is so far developed, at least, that strange faces are at once known as strange, and are distinguished from those of parents and nurse; for they excite astonishment or fear (crying) while the faces of the latter do not. But the latter, if absent, are not yet, at this period, missed by most children. Hence it is worthy of note that a girl in her twelfth month recognized her nurse after six days' absence, immediately, "with sobs of joy," as the mother reports (Frau von Struempell); another recognized her father, after a separation of four days, even in the tenth month (Lindner).