The aim of the present study was to investigate the role of similarity in memory retrieval processes by employing similarity-judgment tasks and computational models. Five conditions of similarity-judgment tasks of Kanji characters were first conducted to 195 university students. Correlational analyses indicated that the similarity among the targets was primarily dependent on their figural feature rather than the semantic or phonetic feature, and moreover, the similarity was significantly correlated with the retrieval order of the targets during a memory retrieval task (Jimura et al., 1999). Then, the similarity space constituted by the shape of the targets was applied to two computational models in subsymbolic level : the multi-dimensional scaling (MDS) and the Isometric feature mapping (Isomap). Dimensional reduction of the shape-based similarity space indicated that the Isomap more accurately represented the similarity derived from the judgment-task and the retrieval pattern than the MDS. These results suggest the importance of the similarity in memory retrieval processes and the superiority of Isomap as a subsymbolic model of similarity.
As a key branch of CBT (computer-based testing), RIT (randomized item testing) is defined and discussed. CBT is now familiar as an innovative method for measuring an amount of acquired knowledge of an examinee. Techniques for precise measurement of knowledge is getting more importance in the present society because of the increasing need for the acreditation to qualify intelligent professions. We begin with noting that CBT contains various different aspects. An important one is measurement of an amount of knowledge. To distingush the most important aspect in CBT from others, we introduce RIT. It is noted that the two key factors of RIT are a well-prepared and well-maintained item pool and a set of items randomly sampled from the item pool. Various difficulties, which arise in traditional testing, can be mitigated by applying RIT. It is emphasized that such difficulties are associated with those in scientific epistemology. We identify the four major steps in the test construction process by RIT, and duscuss the relation of each step with the purpose of measurement.