ABSTRACT
This book has ranged widely over several countries of the world, and it has drawn on many psychological theories and investigations. Throughout, however, it has drawn attention to, and expressed concern over, the differences between peoples in their level of technological advance, of education and civilisation or backwardness. Although the psychologist' tests are highly inadequate instruments for bringing out the full strengths and weaknesses of different groups or individuals, particularly when applied outside the cultural group for which they were constructed, they nevertheless tend to confirm our everyday observations. Each group certainly shows variations in patterns of abilities: members of an underdeveloped country may reach, or surpass, western standards on some tests, and fall below what we would regard as the borderline for mental deficiency on others. But the average performance on quite a wide range of tests only too strikingly fits in with the observed inequalities of mankind. Similarly, within any one western country, there are obvious differences in the status, vocational and educational achievements of subgroups such as the social classes, the coloured immigrants in Britain, the negroes and Indians of North America; and however open to criticism our tests of intelligence and other abilities may be, they tend to reflect these differences.
