The "pure-study" learning curve: The learning curve without cumulative testing

The customary assumption in the study of human learning using alternating study and test trials is that learning occurs during study trials and that test trials are useful only to measure learning. In fact, tests seem to play little role in the development of learning, because the learning curve is similar even when the number of test trials varies widely (Tulving, Journal of Verbal Learning and Verbal Behavior 6:175-184, 1967). However, this outcome seems odd, because other research has shown that testing fosters greater long-term learning than does studying. We report three experiments addressing whether tests affect the shape of the learning curve. In two of the experiments, we examined this issue by varying the number of spaced study trials in a sequence and examining performance on only a single test trial at the end of the series (a "pure-study" learning curve). We compared these pure-study learning curves to standard learning curves and found that the standard curves increase more rapidly and reach a higher level in both free recall (Exp. 1) and paired-associate learning (Exp. 2). In Experiment 3, we provided additional study trials in the "pure-study" condition to determine whether the standard (study-test) condition would prove superior to a study-study condition. The standard condition still produced better retention on both immediate and delayed tests. Our experiments show that test trials play an important role in the development of learning using both free-recall (Exps. 1 and 3) and paired-associate (Exp. 2) procedures. Theories of learning have emphasized processes that occur during study, but our results show that processes engaged during tests are also critical.