The contextual interference effect in motor learning refers to the interference that results from practicing a task within the concept of other tasks in a practice session. Several studies have shown that practice under conditions of high contextual interference, with a random practice order, degrades performance during acquisition trials, compared to low contextual interference conditions, with a blocked order, where practice is completed on one task before practice on another task is undertaken. In contrast to acquisition performance, random practice usually leads to more effective learning than blocked practice, as measured by retention and transfer tests [Timothy et al 1992].

Research findings show that less variability produces better short-term benefits while more variability is often associated with better long-term retention and transfer effects [Edwards et al 1985, Proteau et al 1994]. Random practice increases the difficulty level of performance, thus producing a temporary setback in performance, but it may increase long-term retention rates [Shea et al 1979, Lin et al 2008, Lin et al 2009] .

There exist two opposing arguments in the above paradoxical phenomena, contextual interference and the variability effect.

• One argument states that increased contextual interference or variability decreases initial performance.
• The second, opposing argument states that increased contextual interference or variability increases lasting retention.

These counter intuitive findings are perplexing to most of us who are conditioned to linear thinking patterns, such as “what starts well ends well.” To apply this principle in teaching, it is important to remember that the level of interference and variability should be compatible with age, skill level, time allotted for practice, and instructional resources. Knowing the pros and cons of each argument in the paradox allows the student and teacher to move to the next stage of resolving the paradox. High contextual interference resulting from introducing multiple tasks and placing high variability demands on students for quick reactions tend to favor older, more skilled students who are provided with a lot of support [Chen 2011].

To increase the amount of contextual interference or chaos, the teacher may increase the degree of unpredictability in presenting multiple skills during practice (i.e., random practice). To lower contextual interference, the teacher can use a blocked practice schedule in which only one skill is drilled over and over until it is mastered before moving on to another skill [Chen 2011].

As an example, blocked practice may be instrumental for beginners to develop a stable pattern of movement, but it may also prevent students from moving to the next stage of expertise. Random practice is difficult for beginners who have not mastered the mechanics of basic skills, but it may promote specificity of training for highly skilled athletes.

The second paradoxical phenomena is “Less is more” as with “order out of chaos” it is a perplexing phenomena for most teachers. The main responsibility of teachers and coaches is to provide guidance for students and athletes in the form of verbal instructions, and feedback about the results of their performances. Guidance normally conjures up positive connotations, for it is associated with improvement. “More is better” is often the motto. We want our students to perform well, so the temptation is to provide them with as much guidance as possible. However, motor-learning research has proven that excessive guidance harms long-term learning, while reduced guidance can facilitate it [Salomi et al 1984]. In my experience with coaching teachers this is often where I see less experienced teachers struggle the most, they are so eager to help their students succeed that they forget this important paradox and it’s implications.

Understanding paradoxes such as “less is more” can improve teaching effectiveness.

– David Chen

If we engage in a bit of creative paradoxical thinking, we can couple the above motor learning paradoxes with different methods of teaching, providing us with a clear guide of when and how to choose between our different teaching methods and tools. For example with beginners we can choose to use a direct instruction, frequent feedback, and blocked practice approach, to support our students initial acquisition. As the learning progresses, we can transition to a inductive approach, decrease the frequency of our feedback, and use random practice with a high contextual interference, to support retention and transfer for our more experienced students.

Understanding the implications of these paradoxes , order out of chaos and less is more can help inform our teaching, if we start paying close attention to our students progress we can choose the right approach at the right time.

• Using blocked practice to help beginners develop stable movement patterns,
• Random practice to promote specificity of training for more experienced students.
• Decreasing our guidance and adopting a question based approach, to help more experienced students progress and develop their problem solving skills.

By doing so, we create an optimal learning environment for our students by carefully matching their experience, skill level and our instructional resources to their learning conditions.