When we administer educational achievement tests, we want to be confident that the resulting scores validly indicate what the test takers know and can do. However, if the test is perceived as low stakes by the test taker, disengaged test taking sometimes occurs, which poses a serious threat to score validity. When computer-based tests are used, disengagement can be detected through occurrences of rapid-guessing behavior. This empirical study investigated the impact of a new effort monitoring feature that can detect rapid guessing, as it occurs, and notify proctors that a test taker has become disengaged. The results showed that, after a proctor notification was triggered, test-taking engagement tended to increase, test performance improved, and test scores exhibited higher convergent validation evidence. The findings of this study provide validation evidence that this innovative testing feature can decrease disengaged test taking.