1. The fact that the psychical development of man is regularly slower than that of most animals is to be seen in the much more gradual maturing of his sense-functions. The child, to be sure, reacts immediately after birth to all kinds of sense-stimuli, most clearly to impressions of touch and taste, with the least certainty to those of sound. Still, it is impossible to doubt that the special forms of the reaction-movements in all these cases are due to inherited reflexes. This is especially true for the child's crying when afected by cold and tactual impressions, and for the mimetic reflexes when he tastes sweet, sour, or bitter substances.
It is probable that all these impressions are accompanied by obscure sensations and feelings, yet the character of the movements can not be explained from the feelings whose symptoms they may be considered to be, but must be referred to connate central reflex tracts.
Probably nothing is clear in consciousness until the end of the [p.
284] first month, and even then, as the rapid change of moods shows, sensations and feelings must be relatively very changeable. It is at about this time that we begin to observe symptoms of pleasurable and unpleasurable feelings in the child's laughter and in lively rhythmical movements of his arms and legs after certain impressions. Even the reflexes are not completely developed at first -- a fact which we can easily understand when we learn from anatomy that many of the connecting fibres between the cerebral centres do not develop until after birth. Thus the associative reflex-movements of the two eyes are wanting. From the first each of the eyes by itself generally turns towards a light, but the movements of the two eyes are entirely irregular, and it is only in the course of the first three months that the normal coordination of the movements of the two eyes with a common fixation-point, begins to appear. Even then the developing regularity is not to be regarded as a result of complete visual perceptions, but, quite the reverse, as a symptom of the gradual functioning of a reflex-centre, which then renders clear visual perceptions possible.
2. It is, generally speaking, impossible to gain any adequate information about the qualitative relations of psychical elements in the child's consciousness, for the reason that we have no certain objective symptoms.
It is probable that the number of different tonal sensations, perhaps also the number of color-sensations, is very limited. The fact that children two years old not infrequently use the wrong names for colors ought not however, to be looked upon as unqualified evidence, that they do not have the sensation in question. It is much more probable that lack of attention and a confusion of the names is the real explanation in such cases.
Towards the end of the first year the differential of feelings and the related development of the various emotions [p. 285] take place, and show themselves strikingly in the characteristic expressive movements that gradually arise. We have unpleasurable feelings and joy, then in order, astonishment, expectation, anger, shame, envy, etc. Even in these cases the dispositions for the combined movements which express the single emotions, depend upon inherited physiological attributes of the nervous system, which generally do not begin to function until after the first few months, in a way analogous to the combined innervation of the ocular muscles. As further evidence of this we have the fact that not infrequently special peculiarities in the expressive movements are inherited by whole families.
3. The physical conditions for the rise of spacial ideas are connate in the form of inherited reflex-connections which make a relatively rapid development of these ideas possible. But for the child the spacial perceptions seem at first to be much more incomplete than they are in the case of many animals. There are manifestations of pain when the skin is stimulated, but no clear symptoms of localization. Distinct grasping movements develop gradually from the aimless movements that are observed even in the first days, but they do not, as a rule, become certain and consciously purposive until aided by visual perceptions, after the twelfth week. The turning of the eye toward a source of light as generally observed very early, is to be regarded as reflex. The same is true of the gradual coordination of ocular movements. Still it is probable that along with these reflexes there are developed spacial ideas, so that all we can observe is the gradual completion of these ideas from very crude beginnings, for the process is continuous and is always interconnected with its original physiological substratum. Even in the child the sense of sight shows itself to be decidedly more rapid in its development than the sense of touch, for the symptoms [p. 286] of visual localization are certainly observable earlier than those of tactual localization, and the grasping movements, as mentioned above, do not reach their full development until aided by the sense of sight.
The field of binocular vision is much later in its development than that of monocular vision. The latter shows itself in the discrimination of directions in space. The beginnings of the development of a field for binocular vision coincide with the first coordination of ocular movements and belong, accordingly, to the second half of the first year. The perception of size, of distance, and of various three-dimensional figures remains for a long time very imperfect. Especially, distant objects are all thought to be near at hand, so that they appear relatively small to the child.