Understanding encoding inhibition, retrieval inhibition and destructive interference effects of errors during practice

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PIs Pavlik, Koedinger
Faculty Koedinger
Postdocs Pavlik
Others with > 160 hours n/a
Learnlab None (stimuli from Chinese learnlab)
Number of participants 80 (71 complete data)
Total Participant Hours 100
Datashop? No


The hypothesis is that errors during learning reduce performance through causing some sort of interference effect. Essentially the question is if you get item A wrong at time t, does that effect the chance of getting B wrong at time t+1. If such effects occur then the model of practice used for optimized scheduling will need to be revised to be more accurate. Such an improvement in accuracy should then translate to increased gains for students that have practice controlled by the model.


Research question

Background and significance

Dependent variables

Independent variables



Results contradict the hypotheses. There were no specific effects of errors. This indicates that any effect of errors on reducing performance is more likely to be a non-specific effect, perhaps related to subejct motivation.

However, this experiment also manipualted the intertrial interval between drill trials and set it at either 0ms, 400ms, or 1200ms. This comparison was significant with average performance 61.0%, 62.6%, 64.6%. The result was significant despite the small effect size because of the extremely high within-subject power of this test. Unfortunately, it seems that this difference has a little practical significance because an extra 1.2 seconds per trial is unlikely to be worth a 3.6% increase in performance.



Optimizing the practice schedule

Annotated bibliography