We investigated students' metacognitive experiences with regard to feelings of difficulty (FD), feelings of satisfaction (FS), and estimate of effort (EE), employing either computerized adaptive testing (CAT) or computerized fixed item testing (FIT). In an experimental approach, 174 students in grades 10 to 13 were tested either with a CAT or a FIT version of a matrices test. Data revealed that metacognitive experiences were not related to the resulting test scores for CAT: test takers who took the matrices test in an adaptive mode were paradoxically more satisfied with their performance the worse they had performed in terms of the resulting ability parameter. They also rated the test as easier the lower they had performed, but their estimates of effort were higher the better they had performed. For test takers who took the FIT version, completely different results were revealed. In line with previous results, test takers were supposed to base these experiences on the subjectively estimated percentage of items solved. This moderated mediation hypothesis was in parts confirmed, as the relation between the percentage of items solved and FD, FS, and EE was revealed to be mediated by the estimated percentage of items solved. Results are discussed with reference to feedback acceptance, errant self-estimations, and test fairness with regard to a possible false regulation of effort in lower ability groups when using CAT.