The way physical practice is organized both over short and long time frames determines its outcome. When we talk about movement as a broad concept, it implies that the main interest lies in creating conditions that allow not only for the retention of skills but also an efficient transfer of skills from one area to another. Being good at what you practice is an obvious outcome of repetitive action, but how can you become good at what you don’t do? Contextual interference is one of the concepts we operate with when building the curriculum for our students to achieve this effect.
It is clear that repetition is necessary for learning, but repetition does not necessarily mean an identical action. It can as well be a replication of the same motor program in a different scenario. Variability also plays a significant role in proper learning and can be applied on different levels within the practice. To build an efficient program, we need to take into account both the broad structure in which practice is organized over a long period of time and the structure of a single session. On each level, different parameters apply that dictate whether the learning is taking place and to what extent.
The term contextual interference (CI) comes from information processing research and refers to the structure of a practice that involves constant switching of the tasks which require distinct motor solutions. The structure and degree of the CI can vary within each practice session as well as over bigger time blocks. We can distinguish 3 ways of applying this concept:
- Low CI or blocked practice is a repetition of the same skill over and over again until the learner is able to perform it. The same motor solution is repeated without much variation. This approach will result in executing and adapting a motor pattern for optimal performance, leading to a high outcome in a single practice session.
- Medium CI or varied practice is a schedule that combines different movement tasks requiring similar motor solutions, so it links together the skills that are relevant to each other. It allows the learner to pre-plan and repeat subsequent attempts for a solution.
- High Ci or random practice is structured in a way that does not allow to plan, repeat and compare responses. It allows for quick decision-making and skillful execution of movement patterns linked to picking up perceptual information. It is associated with low performance during the practice but a high retention rate and transfer into a variety of movement tasks.
Each individual experiences different levels of variability in their performance and this depends on multiple factors. Mainly, this will be connected to the experience of a practitioner and their level of skill in each specific domain. The more experienced learners will benefit greatly from a high degree of CI in their day-to-day practice, while the complete beginners will see much more improvement from the blocked schedule. It is not a clear cut, however, and variability should be decreased or increased based on individual parameters and the nature of the task one is engaged with. These two approaches can be combined as needed to obtain the optimal result. In any case, manipulating the task difficulty, both nominal and functional, and the contextual continuum may be a promising route for any practitioner and should be taken into account when building the training schedule. It can be done in many ways, here are some possible examples of tasks variation sources:
1. Tasks that mainly require spatial demands
2. Tasks that mainly require temporal demands
3. Tasks that require both spatial and motor demands
4. Tasks that require both temporal and motor demands
5. Tasks that require spatial, temporal, and motor demands
The underlying mechanisms of the effects of CI are not clear. Two possible explanations are suggested by the researchers: the action plan reconstruction hypothesis and the elaborative processing hypothesis. The first one states that a random practice requires more effortful processing because the action plan for the next solution is forgotten and must be recalled. It is forgotten due to the interference of executing a different preceding action and must be retrieved from the working memory for the next action. In comparison, the blocked practice involves using the same action plan on each trial so no reconstruction process occurs (Lee and Magill, 1983). The second theory suggests that random practice order leads to greater cognitive effort during intra- and inter-task because the skills differ from trial to trial (Shea and Titzer, 1993). Both hypothesis support that error processing increases cognitive effort through the demands associated with switching tasks. When errors occur, learners generate knowledge about future task requirements that subsequently improves their performance. In any case, the beneficial effects of the CI are clear:
- Random practice forces the learner to become more actively engaged in the learning process by preventing simple repetitions of actions.
- Random practice gives the learner more meaningful and distinguishable memories of the various tasks, increasing memory strength and decreasing confusion among tasks.
- Random practice causes the learner to forget the short-term solutions (from working memory) to the movement problem after each task change.
- Forgetting the short-term solution forces the learner to generate the solution again on the task's next trial, which is beneficial to learning.
Contextual interference effect has robust data supporting its efficiency in the retention and transfer of motor skills and it is evident in all task categories except for those that involve the production of segmental movements. Literature shows that “generalized motor program” is not a major determinant of CI effects. There is enough evidence to assume that the adaptations in motor skills that are associated with it involve high-order variables and active cognitive strategies. (Figuiereido, 1993) However, because the effect has been observed in many tasks, it can be interpreted as a basic and general feature of the learning process. In any case, it is clear that high contextual interference, even though causing immediate limited performance, leads to superior performance on retention and transfer of skills.