Until recent years the psychological evaluation of primitive tribes rested largely on the offhand judgments of travelers and missionaries. With the advent of more exact psychological laboratory methods, these have been, in some measure, applied by competent investigators to aboriginal populations. Unfortunately, the results hitherto secured are somewhat meager. There are technical difficulties, among them the necessity of examining fairly large numbers of individuals in order to get a good sample of the population. Worse still, laboratory methods are most effective in regard to what may be called the lower mental operations, which partake almost more of a physiological than of a strictly psychological character. Clearly enough, what we should be most desirous of knowing is how primitive compares with civilized man in logical thought and imagination. But these are precisely the things not readily tested, and here the additional technical difficulty comes in that they can hardly be examined at all without a far more intimate knowledge of the native languages than the investigator is likely to command. Nevertheless, something has been done and I will attempt to present as briefly as possible the essential results, following Thorndike’s convenient summary.[1] Although some observers have attributed unusual acuity of sense perception to the more primitive peoples of the globe, the investigations of Rivers, Woodworth, and others in the main establish the psychic unity of mankind in this regard. For example, though the Kalmuk are renowned for their vision, only one or two of the individuals tested exceeded the European record, and while Bruner found Indians and Filipino inferior in hearing a watch tick or a click transmitted by telephone, the fairness of these tests for natives unused to such stimuli has been reasonably challenged. In their reaction-time tests, widely different groups were very similar. In the tapping test, measuring the rate at which the brain can at will discharge a series of impulses to the same muscle, marked differences were also lacking; but when accuracy as well as rapidity were examined, the Filipino seemed decidedly superior to the whites. Optical illusions were shared by all races tested, which indicates, as Woodworth points out, that simple sorts of judgments as well as sensory processes are common to the generality of mankind. Woodworth subjected his subjects to an intelligence test, demanding that blocks of different shapes be fitted into a board with holes to match the blocks. In speed the average differences between whites, Indians, Eskimo, Ainu, Filipino, and Singhalese are small and there is considerable overlapping. On the other hand, the Igorrote and Philippine Negrito, as well as a group of supposed Pygmies from the Congo, proved remarkably deficient. “This crumb,” concludes our investigator, “is about all the testing psychologist has yet to offer on the question of racial differences in intelligence.”