The paper uses Item Response Theory (IRT) for modeling and hypothesis testing children’s cogni-tive age-acceleration function – within calibration and standardization of some intelligence test. For this, basically Fischer’s Linear logistic test model (LLTM; Fischer, 1973, 2005) is applied. How-ever, instead of originally decomposing the item difficulty parameters of the Rasch model into certain hypothesized elementary parameters, we now suggest to decompose the person parameter alike. That is, there is a decomposition into a testee’s basic ability parameter and an age-leveled effect due to the developmental stage of the age-group in question. For convenience, we only inter-change testees and items in order to facilitate parameter estimation and model test – of course, the Rasch model is totally symmetric as concerns testees and items. By doing so, all findings in the context of LLTM apply; in particular, pertinent program packages are at our disposal. In order to examine the suggested approach’s feasibility, an empirical example is given. An Analogy test with eight items administered to more than 300 testees aged between 6 and 16, was analyzed. As a matter of fact, the logistic acceleration function proved to fit the data well and best.