Forgetting curves in the testing effect: A bifurcation model explanation
Iris E. Yocarini, Samantha Bouwmeester · 2015
The beneficial effect of testing over restudying has been proven to be quite robust. Hereby, research has mainly focused on finding a crossover interaction. In contrast, this study focused on the underlying processes of the testing effect, by modeling the forgetting curves of the items in the study and test condition. Hereby, we extended the traditional testing effect experiment by including four measurement moments, which varied in timing for each participant. Additionally, the four parameter logistic (4PL) model was used to fit the forgetting curves as an alternative to the popular power law function. This allowed for more freedom in the form of forgetting and allowed us to test the predictions made by the bifurcation model explanation of the testing effect. Based on the bifurcation model explanation, it was hypothesized that the slope of the curves would be similar, while the location of the curves would differ. Overall, 53 students participated in our study. They studied 64 LithuanianDutch word pairs in both the study and test condition and were tested on four time points using cued recall tests. The results showed a clear crossover interaction. Interestingly, the modeled curves showed that the location of the forgetting curve differed per condition, while the slope was similar. Where, forgetting was initiated earlier in the test condition. These findings support the bifurcation model explanation. Additionally, the model predicted the beneficial effect of testing to persist on the long term.