This section is from "Scientific American Supplement Volumes 275, 286, 288, 299, 303, 312, 315, 324, 344 and 358". Also available from Amazon: Scientific American Reference Book.
[Footnote: Die Seele des Kindes Beobachtungen ueber die geistige Entwickelung des Menschen in den ersten Lebensjahren. Von W. Preyer, ordentlichen Professor der Physiologie an der Universitaet und Director des physiologischen Instituts zu Jena, etc. Leipzig: Th. Grieben. 1882.]
This is a large octavo volume, extending to over four hundred pages, and consisting of daily observations without intermission of the psychological development of the author's son from the time of birth to the end of the first year, and of subsequent observations less continuous up to the age of three years. Professor Preyer's name is a sufficient guarantee of the closeness and accuracy of any series of observations undertaken with so much earnestness and labor, but still we may remark at the outset that any anticipation which; the reader may form on this point will be more than justified by his perusal of this book. We shall proceed to give a sketch of the results which strike us as most important, although we cannot pretend to render within the limits of a few columns any adequate epitome of so large a body of facts and deductions.
The work is divided into three parts, of which the first deals with the development of the senses, the second with the development of the will, and the third with the development of the understanding.
Beginning with the sense of sight, the observations show that light is perceived within five minutes after birth, and that the pupils react within the first hour. On the second day the eyes are closed upon the approach of a flame; on the eleventh the child seemed to enjoy the sensation of light; and on the twenty-third to appreciate the rose color of a curtain by smiling at it. Definite proof of color discrimination was first obtained in the eighty-fifth week, but may, of course, have been present earlier. When seven hundred and seventy days old the child could point to the colors yellow, red, green, and blue, upon these being named.
The eyelids are first closed to protect the eyes from the sudden approach of a threatening body in the seventh or eighth week, although, as already observed, they will close against a strong light as early as the second day. The explanation of their beginning to close against the approach of a threatening body is supposed to be that an uncomfortable sensation is produced by the sudden and unexpected appearance, which causes the lids to close without the child having any idea of danger to its eyes; and the effect is not produced earlier in life because the eyes do not then see sufficiently well. On the twenty-fifth day the child first definitely noticed its father's face; when he nodded or spoke in a deep voice, the child blinked. This Professor Preyer calls a "surprise-reflex;" but definite astonishment (at the rapid opening and closing of a fan) was not observed till the seventh month. The gaze was first fixed on a stationary light on the sixth day, and the head was first moved after a moving light on the eleventh day; on the twenty-third day the eyeballs were first moved after a moving object without rotation of the head; and on the eighty-first day objects were first sought by the eyes. Up to this date the motion of the moving object must be slow if it is to be followed by the eyes, but on the one hundred and first day a pendulum swinging forty times a minute was followed. In the thirty-first week the child looked after fallen objects, and in the forty-seventh purposely threw objects down and looked after them. Knowledge of weight appeared to be attained in the forty-third week. Persons were first distinguished as friends or strangers in the sixth month, photographs of persons were first recognized in the one hundred and eighth week, and all glass bottles were classified as belonging to the same genus as the feeding-bottle in the eighth month.
With regard to the sense of hearing, it is first remarked that all children for some time after birth are completely deaf, and it was not till the middle of the fourth day that Professor Preyer obtained any evidence of hearing in his child. This child first turned his head in the direction of a sound in the eleventh week, and this movement in the sixteenth week had become as rapid and certain as a reflex. At eight months, or a year before its first attempts at speaking, the infant distinguished between a tone and a noise, as shown by its pleasure on hearing the sounds of a piano; after the first year the child found satisfaction in itself striking the piano. In the twenty-first month it danced to music, and in the twenty fourth imitated song; but it is stated on the authority of other observers that some children have been able to sing pitch correctly, and even a melody, as early as nine months. One such child used at this age to sing in its sleep, and at nineteen months could beat time correctly with its hand while singing an air.
Concerning touch, taste, and smell, there is not so much to quote, though it appears that at birth the sense of taste is best developed, and that the infant then recognizes the difference between sweet, salt, sour, and bitter. Likewise, passing over a number of observations on the feelings of hunger, thirst, satisfaction, etc., we come to the emotions. Fear was first shown in the fourteenth week; the child had an instinctive dread of thunder, and later on of cats and dogs, of falling from a height, etc. The date at which affection and sympathy first showed themselves does not appear to have been noted, though at twenty-seven months the child cried on seeing some paper figures of men being cut with a pair of scissors.
In the second part of the book it is remarked that voluntary movements are preceded, not only by reflex, but also by "impulsive movements," the ceaseless activity of young infants being due to purposeless discharges of nervous energy. Reflex movements are followed by instinctive, and these by voluntary. The latter are first shown by grasping at objects, which took place in Preyer's child during the nineteenth week. The opposition of the thumb to the fingers, which in the ape is acquired during the first week, is very slowly acquired in the child, while, of course, the opposition of the great toe is never acquired at all; in Preyer's child the thumb was first opposed to the fingers on the eighty-fourth day. Up to the seventeenth month there is great uncertainty in finding the mouth with anything held in the hand--a spoon, for instance, striking the cheeks, chin, or nose, instead of at once going between the lips; this forms a striking contrast to the case of young chickens which are able to peck grains, etc., soon after they are hatched. Sucking is not a pure reflex, because a satisfied child will not suck when its lips are properly stimulated, and further, the action may be originated centrally, as in a sleeping suckling. At a later stage biting is as instinctive as sucking, and was first observed to occur in the seventeenth week with the toothless gums. Later than biting, but still before the teeth are cut, chewing becomes instinctive, and also licking. Between the tenth and the sixteenth week the head becomes completely balanced, the efforts in this direction being voluntary and determined by the greater comfort of holding the head in an upright position. Sitting up usually begins about the fourth month, but may begin much later. In this connection an interesting remark of Dr. Lauder Brunton is alluded to ("Bible and Science," page 239), namely, that when a young child sits upon the floor the soles of his feet are turned inward facing one another, as is the case with monkeys. When laid upon their faces children at earliest can right themselves during the fifth month. Preyer's child first attempted to stand in the thirty-ninth week, but it was not until the beginning of the second year that it could stand alone, or without assistance. The walking movements which are performed by a child much too young to walk, when it is held so that its feet touch the ground, are classified by Preyer as instinctive. The time at which walking proper begins varies much with different children, the limits being from eight to sixteen months. When a child which is beginning to walk falls, it throws its arms forward to break the fall; this action must be instinctive. In the twenty-fourth month Preyer's child began spontaneously to dance to music and to beat time correctly.