In athletics, the concept has been referred to as "variable practice" (illustrated by this early study on badminton serves). The application of the concept is not complicated. In the badminton study, for example, the experiment simply involved running groups of athletes through serving drills, some practicing one type of serve at a time ("blocking"), while other groups ran drills that varied the type of serve within each drill. When the performance of the groups was measured, the groups that used variable practice outperformed the rest.
Though researchers were unsure how well the concept would work in different settings, further investigation has shown the concept to be broadly applicable. One study measured medical students' abilities to diagnose accurately from electrocardiogram results. In a significant study from 2011, researchers found that even critical thinking or complex judgement tasks could be improved with the application of random introduction, practice, and review of concepts.
The term "interleaving," with its more bookish image, has been used to describe the techniques of designing a course of learning in which different categories are mixed randomly and spaced out over the learning program. Like sports practice, a given category or topic in the course is halted and another introduced before the first category is completed, say, and then review of categories is also accomplished with a random mix. While the learner might experience this lack of completed category blocks as disruptive--and indeed, blocking versus random methods improves short-term memory as well as the feeling among learners that they are learning successfully--the interruptions and random order of exposure change the way the brain builds a strong path to the memory. As we have seen in prior posts, this "desirable" difficulty enhances the brain's ability to retrieve the information later.
In an organizational context (and not in a school, where much of the research we are reading about is focused), the primary question is: what kinds of knowledge might be most effectively transmitted using these methods? How do organizations assess the goals of a learning project that clearly delineate the long-term over short-term needs? And how might we account for the possibility of frustration among learners who might experience such methods as initially ineffective?
Original author: Jenna Smith