Results
In Experiment 1, participants who justified their answers scored about 10% higher on the test than those who did not. Importantly, that’s their MC correctness; the researchers didn’t examine their actual justifications (which happens to be great news for busy teachers). When looking at how students thought they would do, there was an interesting interaction. Participants who knew they were going to have to justify their answers were a bit underconfident in how they would perform compared to those who just took the MC test, who were overconfident. But then, after taking the test, both groups were pretty similar in metacognition.
This metacognitive effect is important. One of the benefits of retrieval practice is improved metacognition. By reducing overconfidence, students are more likely to persist in self-directed studying. Simply telling them they will need to explain their answers provided this same benefit that both groups received after practicing retrieval.
In a second experiment, the researchers wanted to see if this effect persisted over a delay, so participants were asked to take the MC test again two days later. While the answer justification group still scored 6% higher, the effect wasn’t significant. This could be due to their smaller sample size, but does give this blogger a little bit of pause. Often, we see that a strategy has an immediate effect that disappears or reverses over time. Given the mechanisms here, I highly doubt that is the case for this study, but further research is certainly needed.
