Abstract: Cast from the perspective of cognitive processing in test item solution, the assumptions underlying psychometric models within various testing theories were analyzed. Although item response mechanism is neglected as definition in CTT and GT, it is included as an integrated component in IRT. Unlike early IRT models where the relevant assumptions are made statistically and lack substantive psychological justifications, assumptions in cognitive psychometric models are explicitly tuned to specific situations of test item solution, which provide a foundation for cognitive approach to psychological measurement. A variety of cognitive psychometric models are synthesized and discussed according to a categorization of item response mechanism.

Key words: psychometric model, item response process, cognitive psychometric model