The Coloured Progressive Matrices Test (CPM), a measure of inductive reasoning ability, has been reported to correlate .91 with WISC Full Scale IQ. Each item of the CPM Test displays a pattern with a section missing; below it are six response alternatives, one of which would correctly complete the pattern. New and presumably better self-instructional sequences were used with both first- and third-grade Ss. Trained Ss did no better than controls on a CPM posttest. The test, however, appeared to confound “pure” inductive ability with ability to imagine how a response alternative would look if inserted into the pattern. A new test format was developed to eliminate the role of the latter by having S judge the correctness of already completed patterns. Dramatic increases in test scores were found. Apparently the advantage of two years' mental growth that third-graders have over first-graders on the conventionally administered CPM derives in large part from improved power of imagining how a distractor would look in a new location, rather than of inductive reasoning ability. With the new test format Ss were significantly better able to accept correctly completed than to reject incorrectly completed matrices. Among first-graders, this tendency was significantly stronger for trained than for control Ss.