Perceived test importance and test-taking effort are typically measured after test completion, contrary to the temporal ordering specified by expectancy-value theory. Retrospective importance and effort scores may reflect students' self-protective attributions of performance, which would support collection of prospective importance and effort scores. Experiencing the test, however, may result in more accurate retrospective scores than prospective scores. Because there has been little empirical research regarding if and how self-reported prospective and retrospective scores differ, we had a random sample of students provide importance and effort ratings before (prospective) and after (retrospective) a low-stakes cognitive test. Given longitudinal invariance of importance and effort scores, we found latent effort scores decreased on average and changed relative rank-order from before to after the test. These individual differences in change in effort were not predicted by test performance. Lower retrospective scores imply different conclusions could be made depending when effort is measured relative to test completion.