Varied practice

In the study of learning and memory, varied practice (also known as variable practice or mixed practice) refers to the use of a training schedule that includes frequent changes of task so that the performer is constantly confronting novel instantiations of the to-be-learned information.

The varied practice approach focuses on the distribution of practice in time, the organization of activities to be practiced (blocked vs. random), and the interleaving of information or content to highlight distinctions that facilitate learning. For example, a varied practice approach to learning to shoot a basketball might involve a sequence of ten mid-range jump shots, followed by ten lay-ups, followed by ten free-throws, followed by ten three-pointers, with the entire cycle repeating ten times. This contrasts with traditional approaches in which the learner is encouraged to focus on mastering a particular aspect or subset of the relevant information before moving on to new problems (e.g., focusing on free-throws before moving to three pointers). With varied practice, the learner is exposed to multiple versions of the problem even early in training.

In many learning domains, varied practice has been shown to enhance the retention, generalization and application of acquired skills. There are many potential sources of the observed advantages. First, greater diversity of the tasks may also allow learner to extract the most relevant, task-invariant information. Any given practice trial contains both task-relevant and task-irrelevant information. By mixing up the trials, task-irrelevant information will be less consistent, allowing the learner to strip away the spurious associations. Task-relevant information should be constant regardless of the particulars of individual trial. Second, varied practice creates conditions that are likely to encourage elaborative rehearsal (see Craik & Tulving, 1975). Elaborative rehearsal is a means by which the learner forms multiple associations with the to-be-learned material, so that it can be recalled using a variety of cues. Cognitive psychologists generally regard elaborative rehearsal as one of the most effective means of acquiring new information, and its basic logic – to study the material from a range of perspectives in order to former richer links with preexisting knowledge – is completely consistent with the varied practice approach. Finally, because learners are frequently changing tasks, practice may seem less repetitive, potentially minimizing boredom and increasing the level of engagement during practice.

The theoretical underpinnings of the varied practice approach stem primarily from a behavioral phenomenon discussed in the skill acquisition literature called contextual interference (Shea & Morgan, 1979). Contextual interference refers to a learning benefit observed when the items to be learned are randomly intermixed across training blocks rather than repeated in blocks (for a review, see Magill and Hall, 1990). That is, when identical items are blocked together during training, post-training performance is worse than when different items are intermixed. Although primarily studied with motor skill learning task, contextual interference was originally reported in a verbal paired associates task (Battig, 1966, 1972) and has been observed in other nonmotor tasks (e.g., Carlson et al., 1989). Intriguingly, the benefits of mixed-item blocks are apparent only some period of time after practice, indicating that the effects are primarily long-term.

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