Too hard, too easy, or just right? The relationship between effort or boredom and ability-difficulty fit

Usually, it is assumed that achievement tests measure maximum performance. However, test performance is not only associated with ability but also with motivational and emotional aspects of test-taking. These aspects are influenced by individual success probability, which in turn depends on the ratio of individual ability to item difficulty (ability-difficulty fit). The impact of ability-difficulty fit on test-taking motivation and emotion is unknown and rarely considered when interpreting test results. N = 9,452 ninth-graders in Germany (PISA 2006) completed a mathematics test and a questionnaire on test-taking effort (motivation) and boredom/daydreaming (emotion). Overall, mean item difficulty exceeded individual ability. Ability-difficulty fit was positively linear related with effort and boredom/daydreaming.The results suggest that low ability students may not show maximum performance in a sequential achievement test. Thus, test score interpretation for this subsample may be invalid. As a solution to this problem the application of computerized adaptive testing is discussed.