Numerical evaluation of scientific activities is criticized for quantifying what cannot be measured and for taking a life of its own, while it attracts huge expectation. These problems are not particular to the issue of scientometrics. Psychology, which has tried to reveal an ambiguous research object, the “mind”, in a scientific manner, has confronted difficulties and social pressure of numerical evaluation. The history of intelligent quotient (IQ) shows the process in which a particular way of numerical evaluation of intelligence has been standardized, used for discrimination and became diffused. This article discusses the mechanism and problems of the numerical evaluation through reviewing the development of IQ in the social context by focusing on the decontextualization of figures.