Testing the retrieval effort theory

Testing effect refers to the phenomenon that, relative to relearning, retrieval practice enhances delayed memory performance. In two experiments, this study tested the retrieval effort theory proposed to explain the enhancement effect of testing. In Experiment 1, participants learned English words with their corresponding Chinese definitions. Then they were tested on half of the encoded items and restudied the remaining half under three delays after encoding (0 min, 20 min, and 40 min). All participants took delayed memory tests 60 min after the end of the initial encoding phase. The result showed that testing conducted 20 min after encoding, but not immediately or 40 min after encoding, enhanced memory retention. In Experiment 2, feedback was provided to ensure more equitable exposure across the conditions, and then the final memory test was conducted 24 h after the end of learning. The result showed that testing enhanced memory retention across the three delay conditions, and that the size of the testing effect increased with the extension of the interval between initial learning and retrieval practice, thus providing support for the retrieval theory.