That the fourth element pointed out above is a real source of confusion is shown by the fact that children recognise many words which they can not readily pronounce. When this was realized, a second phase in the development of the problem arose. A colour was named, and then the child was required to pick out that colour. This gave results different from those reached by the first method, blue and red leading the list in correct answers by the first method, while by this second method yellow led, and blue came near the end of the list.
The further objection that colours might be distinguished before the word names are learned, or that colour words might be interchanged or confused by the child, gave rise to what we may call the third stage in the statement of the problem. The method of "recognition" took the place of the method of "naming." This consisted in showing to a child a coloured disk, without naming it, and then asking him to pick out the same colour from a number of coloured disks.
This reduces the question to the second of the four I have named above. It is the usual method of testing for colour blindness, in which, from defects of vision, certain colours can not be perceived at all. It answers very well for colour blindness; for what we really want to learn in the case of a sailor or a signal-man is whether he can recognise a given signal when it is repeated; that is, does he know green or red to be the same as his former experience of green or red? But it is evident that there is still a more fundamental question in the matter--the real question of colour perception. It is quite possible that a child might not recognise an isolated colour when he could really very well distinguish the colours lying side by side. The last question, then, is this: When does the child get the different colour _Sensations_ (not recognitions), and in what order?
To solve this question it would seem that experiments should be made upon younger children. The results described above were all secured after the children had made considerable progress in learning to speak.
To meet this requirement another method may be used which can be applied to children less than a year old. The colours are shown, and the child led to grasp after them. This method is of such a character as to yield a series of experiments whose results are in terms of the most fundamental movements of the infant; it can be easily and pleasantly conducted; and it is of wide application. The child's hand movements are nearly ideal in this respect. The hand reflects the child's first feelings, and becomes the most mobile organ of his volition, except his organs of speech. We find spontaneous arm and hand movements, reflex movements, reaching-out movements, grasping movements, imitative movements, manipulating movements, and voluntary efforts--all these, in order, reflecting the development of the mind.