The human response and information processing in control tasks is affected by psychological states as well as physiological limitations. Therefore, investigating their effects, the realization of man-machine systems which are able to compensate for human errors and carelessness is required. From this point of view, problems of inattention have been studied in various ways. Also, it is well known that vagueness associated with mental phenomena could be described by the concept of ‘Fuzzy’. Accordingly, in this paper, the fraction of attention is considered on the basis of the ‘Fuzzy Entropy’ as a trial approach. Numerical estimations for human operator attention allocation are calculated and the types of the membership functions of the fuzzy set are tested as the human subjective evaluation.
As a result, it is found that the ‘psychological entropy’ defined by the maximum fuzzy entropy with respect to the ‘incidence probability’ produces the optimal attention allocation and the number of the effective displays is 3 or 4. The method presented in this paper is also compared with the other model to demonstrate the validity.