Where representative drawing has been isolated for study in relation to general intelligence, no results contradictory to the conclusions stated above have been reported. Earlier investigators had declared that great talent for graphic expression is closely connected with good intellectual endowment in children, but that “the reverse of this does not hold true.” This conclusion will probably be shown to be well founded in future researches carried out by modern test methods. “Great talent” includes much more than mere ability to “see and make” an object. As Manuel says, “Before one gets very far in art expression, a great number of supplementary factors must be brought to the support of the ability to represent graphically simple objects. Even the technique itself becomes progressively more difficult.... General intelligence conditions the ability of drawers (a) to acquire the advanced technique into which conceptual factors enter, and (b) to create original drawings of merit.”
Manuel also gave tests of linguistic ability in the course of his study and found no essential relationship between ability to draw and ability to manage words. “Linguistic ability is no index of ability or lack of ability in graphic representation,” but linguistic ability correlates well with general intelligence (as has been previously emphasized in this volume).
For purposes of educational and vocational guidance we now need especially studies of the relationship between general intelligence and kinds of drawing other than the representative. We require studies of the extent to which copying, analytical drawing, symbolic drawing, and caricature are correlated with general mental capacity. It may be predicted with some confidence that research in unselected groups will finally show copying and representative drawing to be slightly correlated with general intelligence. Analytical and symbolic drawing are probably significantly correlated with general intelligence, while caricature is doubtless very closely correlated with intellectual capacity.
We need also researches bearing upon the relationship between ability in painting, sculpture, and pattern-cutting, and general intelligence. To what extent are painters and sculptors of high repute also gifted with superior intellectual acumen? Popular opinion would have it that the “artistic mind” is antagonistic in its organization to the “scientific mind.” Probably here as elsewhere uncontrolled speculation leads to false conclusions. Probably those who achieve eminence in the arts are, on the whole, as highly endowed with general intelligence as are those who win eminence in other kinds of careers. Greatness in graphic portrayal almost certainly results only when there is a rare combination of highly specialized capacity for representative drawing, and very high IQ, in the same individual.
Fortunately for all, modern life calls for all forms of talent in drawing, in all degrees of combination with general intelligence. Sign painters, copyists, designers, draughtsmen, architects, illustrators, and creative interpreters of human faces and of human life are all needed. Persons skilled in drawing are essential to mechanical and industrial development in society, for everything made must first be drawn, from the motor of an airplane to the fancy buttons on a child’s coat.
V. THE COLOR-BLIND
Between 3 and 5 per cent of boys, and apparently fewer girls, inherit a special defect of vision, called “color blindness.” A color-blind child may be gifted in drawing, except in color drawing, but he will be incompetent as a painter.
There are several forms of this special defect. Very rarely it may happen that no discrimination among colors is possible, the world appearing, as in a photograph, to consist only of light and shade. In the late evening, or in any sufficient dimness, color is not perceived by ordinary eyes. Those who are blind to all colors do not see color with the brightening of the light, as ordinarily happens.
The most common form of color blindness is, however, that in which only red-green sensations are absent, other colors being distinguishable. There is no disease present in such cases. The defect is hereditary, and consists in deviation from the typical in structure of the retina. The eyes of color-blind persons are as healthy and normal as those of others, in respect to functions other than acting as receptors for certain waves of light.
A few cases of blue-yellow color blindness have been reported, these resulting from pathological causes.