When is guessing incorrectly better than studying for enhancing memory?

Recently, Kornell, Hays, and Bjork (Journal of Experimental Psychology: Learning, Memory, and Cognition 35:989-998, 2009) demonstrated that incorrect guessing can benefit subsequent memory to a greater degree than can an equivalent amount of study time. We explored this intriguing finding to determine which factors moderate the advantage of incorrect guessing relative to study. In contrast to the findings of Kornell et al., our Experiment 1 revealed that incorrect guessing resulted in worse performance than did studying and that the number of incorrect guesses did not moderate the effect. In contrast, Experiment 2 revealed that the timing of subsequent study moderated the effectiveness of incorrect guessing over study. Final test performance was greater for incorrectly guessed items than for prestudied items when a subsequent study opportunity occurred immediately after the pretrial, whereas the pattern reversed when subsequent study was delayed. This crossover interaction emerged largely because prestudy items showed a classic spacing effect, whereas the guess items did not. One plausible explanation for the absence of a spacing benefit for guess items is that delaying the subsequent study trial increases source-monitoring errors during retrieval, such that participants confuse their original guess with the correctly studied target. However, Experiment 3 provided evidence against this source-monitoring account. We concluded by discussing other possible accounts of why the timing of study could moderate the effectiveness of incorrect guessing.