Effects of repeated retrieval on keyword mediator use: shifting to direct retrieval predicts better learning outcomes

Keyword mediators are an effective memory technique to encode novel vocabulary: learners link
a novel word form to its meaning with a mental image that includes a keyword that resembles
the word form (e.g., nyanya = tomato; keyword mnemonic: the ninja chops the tomato in half).
Prior research suggests that such mediated form-meaning associations become less dependent
on keywords after retrieval practice. The present study investigated if retrieval-induced
decreases in mediator use predict word retention. Thirty participants learned novel
vocabulary using experimenter-provided keywords and repeatedly retrieved the words from
memory while thinking aloud. As expected, keyword use decreased with practice: learners
stopped mentioning keywords for 21.6% of the words (on average after 8.27 retrievals).
Shifting to direct, unmediated retrieval predicted higher form and meaning recall on a
retention test after 6–8 days. Continuing retrieval practice until a shift has occurred to direct
retrieval thus seems beneficial for retention.