XIII. THE FREQUENCY OF MARKED SPECIAL TALENTS AND DEFECTS
No census of special talents or defects of given degree has ever been taken. Surveys have been made showing the distribution of musical sensitivity, of ability in drawing, spelling, calculation, and so forth. These distributions tell us the frequency of extreme deviations in these functions, but they do not tell us to what extent the deviations are special. From them we cannot learn whether or not the extremely fortunate deviations are identified with great general superiority, and whether the unfortunate deviations represent the work of generally stupid children. What we require is a survey of children of uniform age, educational opportunity, and IQ, in respect to music, drawing, spelling, and so forth.
Although we cannot state with precision the frequency with which marked special gifts occur among the stupid, or marked special deficiencies occur among the highly intelligent, we know that such cases are quite rare. It is necessary to remind ourselves constantly of this fact, because it would gratify the demand for justice and fair play to find that special gifts are freely distributed among the generally inferior, and special defects frequently found among the superior. The truth which satisfies our desires need be stated but once, to be apprehended and remembered. The truth which offends kindliness, self-interest, or cherished beliefs, and is hence unsatisfying, requires emphasis. Therefore we must take particular care to bear in mind throughout the whole of our discussion of special talents and defects, that we are dealing with comparatively rare phenomena. The distribution of abilities, as determined by biological law, does not correspond to our concept of fair play. Nearly all stupid persons are inferior in all capacities. The great majority of gifted persons are superior in nearly all their abilities. The majority of human beings are neither markedly inferior nor markedly superior, but are “typical” (not far from the median or average) in all respects.