Abstract: Item response theory graded model was used to study Differential Item Function (DIF) between Chinese and Japanese samples on a measure of “environment sensitivity”, which is a subscale of Shiba’s simple personality inventory. Several issues were addressed. The first issue was that proportion of DIF items is rather larger (3/4) on the scale. Second, the DIF items were affected by item content and thresholds, but was not affected by the item discrimination. Third, the Japanese multiple IRFs of the DIF items were more similar than Chinese. It is proposed that identifying cultural differences by using the DIF items. Finally, a topic for future research was suggested

Key words: graded model, Differential Item Functioning, cross-cultural comparative study