The Function of Maintaining Concentration (TAF): An Approach to the Evaluation of Mental Stress

Abstract

If the essential nature of fatigue were to be grasped physiologically or biochemically, there would be no difficulty in finding an appropriate approach to the evaluation of fatigue. However, there seem to be no reliable tests of fatigue among those in current use. For this reason, we initiated a new concept of “the function of maintaining concentration (TAF),” and on the basis of this concept we devised the TAF (Target Aiming Function) test.

Using the TAF test, a series of field investigations and experimental studies was carried out in regard to the autonomic nervous function. In this paper, a few studies on TAF in relation to vigilance are introduced.

Stresses in pilots caused by repeated jet flights and in workers engaged in a vigilance task with and without a conveyer system were studied and experiments were conducted on the relationship between autonomic nervous balance and TAF scores. The results were as follow:

• 1. TAF scores accurately reflected qualitative differences in performing a vigilance task and clerical work, and clarified certain differences among workers on different shifts as well as between conveyer and non-conveyer systems.

• 2. In pilots, the TAF test scores showed significant changes after repeated jet flights in proportion to the degree of their subjective feelings of fatigue.

• 3. The changes caused in the autonomic nervous balance by stress stimuli showed a significant correlation with the changes in TAF scores.