The information processing approach is one of the most popular methods of cognitive science researches. The approach is summarized as follows. First, psychological experiments are designed, and some human subjects participate in the experiments. Secondly, a model of the human thinking processes is constructed based on the experimental results. The model is described in a computer language to perform computer simulations. Finally, the model's behavior in the computer simulations is compared with the human behavior observed in the psychological experiments. If two kinds of behaviors are in agreement with each other, reasonable construction of the model is confirmed. However, human thinking processes include some individual alternations. In the comparison between results of computer simulations and human behaviors, the former represents only a common part of the latter, or a local part of the latter regarded as an important one by the experimenter. Thus, estimation of reasonable construction of the model depends on ambiguous decisions by the experimenter. For the above reasons, we give one of methods where a model represented as production system simulates individual human thinking processes. In this method, we divided the model into three parts: rule set R, parameters t_j, and rule set R′. So a model is represented as follows. R(t_1,t_2,…)+R′Rule set R is constructed of production rules, and corresponds to core parts of the medel. Parameters t_j exist at condition parts or action parts of the production rules in set R, and correspond to individual alternations which are able to be treated within rule set R. Rule set R′is constructed of production rules which are added individually to rule set R, and corresponds to individual alternations which are not able to be treated within rule set R. Moreover, we discuss efficiency of the method through a guessing task of two-dimensional arrangement of cards, which is a kind of inductive inference tasks. As the result, we succeed in computer simulations of individual human thinking processes, and acquisition of new knowledges about human thinking processes.