My research program focuses on evidence-based learning techniques. This work encompasses multiple strategies and subject domains, including: (1) retrieval practice on facts, paired and triple associates, vocabulary, and other materials; (2) interleaved practice for foreign language learning and other materials; (3) spelling instruction with children and adults; and (4) sleep and procedural skills. Collectively, this work is building a toolbox of techniques that accelerates the efficiency and efficacy of student learning.

Retrieval Practice

Taking a practice quiz or test, also called retrieval practice, does not just assess memory; it strengthens it. My research on retrieval practice—one of the most promising techniques in learning science today—seeks to go beyond the empirical “retrieval practice effect” and investigate its scope, its underlying mechanisms, and its ability to yield transferrable learning. This includes work on individual differences in memory ability and retrieval practice (Pan, Pashler, Potter, & Rickard, Journal of Memory and Language, 2015), one of the first quantitative models of retrieval practice effects (Rickard & Pan, Psychonomic Bulletin & Review, 2017), and a comprehensive meta-analytic review of over 40 years (192 experimental comparisons, 67 papers, and > 10,300 subjects) of retrieval practice and transfer research (Pan & Rickard, Psychological Bulletin, 2018).

Instructors often aim for learning to transfer, or generalize, to different contexts. Whether retrieval practice supports transfer has long been an open question. In the first research on this issue involving triple associate words (e.g., “desk-paper-ink”), I discovered that retrieval practice on a word from a triple associate (e.g., “desk”) enhances recall for that word but not unpracticed words (e.g., “ink”). This lack of transfer (Pan, Wong, Potter, Mejia, & Rickard, Memory & Cognition, 2016) identifies an important boundary condition of the technique, helps elucidate its underlying mechanisms, and has practical implications: students should expect strong but selective benefits, particularly when learning related words or concepts. I have extended this line of work to Advanced Placement History and Biology facts (Pan, Gopal, & Rickard, Journal of Educational Psychology, 2016), term-definition facts (Pan & Rickard, Journal of Experimental Psychology: Applied, 2017), scientific concepts (Pan, Hutter, D'Andrea, Unwalla, & Rickard, Applied Cognitive Psychology, 2019), and a comparison of paired and triple associates (Rickard & Pan, under review).

Interleaved Practice

Learning two or more skills or concepts at a time by alternating between them during training (e.g., given concepts A, B and C, using an ABCABC schedule) yields benefits over conventional blocked practice (e.g., using an AABBCC schedule) for motor skills, visual category learning, and math. However, research on educational uses of this technique, called interleaved practice, is still in its infancy (Pan, Scientific American, 2015). For example, there has been little evidence that interleaved practice benefits language learning. In one the first studies to address this issue, I investigated the effectiveness of interleaving vs. blocking for learning Spanish verb conjugation skills (i.e., specifying the correct verb ending for a given pronoun verb/tense combination in either the preterite or imperfect tenses). When training occurred in a single session, interleaving yielded learning that was on par or reduced relative to blocking; when interleaved occurred across two sessions of training, it yielded large benefits over blocking (Pan, Tajran, Lovelett, Osuna, & Rickard, Journal of Educational Psychology, 2018). This suggests that spaced practice, which is an inherent component of interleaving, may be a key contributor to its learning benefits for foreign language learning.

Spelling Skill Acquisition

In 400 years of spelling instruction, minimal research on the efficacy of different methods has occurred under controlled conditions--until now. My investigations of a series of techniques has yielded data on “what works” for the acquisition of this important skill In two large-scale college classroom studies, I found that copying, retrieval practice, and self-directed study are highly effective for teaching adults to spell (Pan, Rubin, & Rickard, Journal of Experimental Psychology: Applied, 2015), while reading and recitation are not (Pan & Rickard, in preparation). Research conducted in elementary school classrooms in collaboration with Angela Jones and John Dunlosky of Kent State University has found that retrieval practice boosts 1st grade spelling skills by over 300% and surpasses an increasingly used method called “rainbow writing” (Jones, Wardlow, Pan, Zepeda, Heyman, Dunlosky, & Rickard, Educational Psychology Review, 2015). All of these findings are of the utmost importance for how spelling should be taught. Accordingly, I am now working on a comparison of modern research findings with historical spelling instructional recommendations (Pan, Rickard, & Bjork, in preparation).

Sleep and Procedural Skills

As part of an additional research direction targeting sleep and procedural learning, I recently published a meta-analysis of sleep and motor skills (Pan & Rickard, Psychological Bulletin, 2015). By performing a meta-regression analysis on a quarter-century of research (88 experimental groups, > 1,200 subjects), I found that, despite what many neuroscience textbooks suggest, there is no evidence for sleep-dependent motor learning mechanisms. Instead, the literature favors a supportive memory stabilization role for sleep (for a follow-up report which arrives at the same conclusions, see Rickard & Pan, Psychological Bulletin, 2017). Further work has examined the role of sleep in visual texture discrimination learning (Walker, Pan, Modir, & Rickard, Journal of Vision, 2014).


Robert Bjork, University of California, Los Angeles
Elizabeth Bjork, University of California, Los Angeles
Timothy Rickard, University of California, San Diego
Hal Pashler, University of California, San Diego
Jim Cooke, University of California, San Diego
Mark McDaniel, Washington University in St. Louis
John Dunlosky, Kent State University
Angela Jones, John Carroll University