Abstract: The present paper has analysed classical threshold theory in psychophy-sics thereby a fuzzy theory of threshold has been developed. The theoryregards the threshold as a critical point between possibility distribu-tions of categories which is characterized by belonging partically to thiscategory, partically to another one on category scales. The ceitical valueis stimulus intensity corresponding to the critical point. Scaling techniqueof the multiple critical points among categories and procedure of determi-nation of the critical value have been given in the work, too.

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