Abstract: The author suggests that there is a general relationship betweenstimulus τ and its effect E, the so-called effect equation E=B log(1+γ),where B is a conditional constant having the same dimension or naturewith that of the corresponding effect E. This new idea is more or less supported by neuro-physiologicalexperiments and is strengthened by considering the fact that. humansensory acceptor organs can respond to stimuli of enormous intensitydifference. It is quite interesting to note that many psychological laws indistinct fields can be unified into one psychological model given by theeffect equation. For instance, from this equation we may derive the lawof forgetting and the Hyman formula of choice reaction time in thefield of experimental psychology, and also various experimental laws inpsychophysics, such as Fechner's law, Weber's law, the Ferry-Porterlaw and the Granit-Harper equation etc. The law of forgetting is thus modified to extend its validity to thetime range 0≤t<1, rendering it more comprehensive. Fechner's law isalso modified, avoiding the appearance of negative sensation. Besides,the relation between effect E and sensation S is discussed. TheGranit-Harper equation viewed in this model has been rendered moreeasily understandable. During the derivation of the Ferry-Porter law the author discoveredan apparent principle with regard to the speed and accuracy of infor-mation porcessing in the brain. Direct tests of the unified model can be obtained by analyzingcertain previously published data. The sample given in this paper is aneuro-physiological experiment on king crabs. Another sample will bepresented in a separate paper where the relationship between reactiontime and stimulus intensity will be dealt with.

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