The Sato Caution Index takes into account the number and difficulty of items gotten wrong by a student within his or her ability, as well as the number and difficulty of items gotten right beyond his or her ability. Sato subtracts the two components to define a single Caution Index. In this study, the components are kept separate, defining a Within Ability Concern Index (W) and a Beyond Ability Surprise Index (B). Using data from 10-item testlets taken by 121 college students, the critical information made available by using the B and W Indexes in addition to the Sato Index is identified. The relationships of the three indexes to total score and the number of errors committed by the students within ability-level are examined. Factor analysis reveals that the new indexes can add a new dimension to test performance information provided by the Sato Index. Five tables provide analysis data. (Author/SLD)