Duolingo-inspired pretesting with words and pictures improves vocabulary learning.

Contemporary language learning applications such as Duolingo and Rosetta Stone often introduce vocabulary through guessing-with-feedback exercises in which learners match words and pictures. We investigated whether that process might yield a pretesting effect-that is, the phenomenon where guessing with correct answer feedback (pretesting) enhances memory. Across four experiments, adult online learners engaged in multiple-choice pretesting to learn Spanish word translations shown in word-image (Experiments 1-2) or image-word (Experiments 3-4) format. Relative to a read-only condition, pretesting yielded statistically significant performance improvements on subsequent cued recall (Cohen's d = 0.18-0.40) and, in most cases, multiple-choice tests (d = 0.25-0.67), regardless of whether test formats were separately presented or intermixed. Participants also reported preferring pretesting over reading for learning second-language vocabulary, especially for word-image learning. Together, these findings extend the pretesting effect to visual and verbal materials, offering theoretical insights and substantiating word-image and image-word guessing-based approaches of language learning.