Abstract: Psychological magnitude associated with respiratory resistive loadis considered as a fuzzy one in this study. A fuzzy set approach calledMultistage Evaluation Scale (MES) was adopted to reveal a possibilitydistribution of this fuzzy magnitude, and a formula for treatment of thedata-- --was used to estimate psychological.magnitude associated with respiratory resistive load. Thirty--seven.healthy young male subjects experienced six levels of suprathresholdadded resistance, loaded at different phases of the breathing cycle. The results revealed that the relationship between resistive load. and perceived magnitude can be expressed by psychophysical powerfunction. The data showed that the severity of the sensory experiencecaused by equal resistive intensity differed significantly when loaded atdifferent phases of the breathing cycle, but the speed of sensory growthdid not manifest significant change. The experiment also showed thatthe physical and physiological magnitudes were correlated to eachsensory category grade of the scale, which may be useful for establishingresistive standards for respiratory protective equipments. We also com-pared and discussed methodology related to MES and classicalcategory scale.

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