The Contextual Interference (CI) effect is the term used to describe the learning outcomes associated with different practice schedules. The CI effect is a term used to describe the findings that optimal levels of complexity (interference) promote learning when it is assessed as performance in retention and transfer tests. In simple terms, it describes levels of effort.
The concept of CI comes from an Information Processing (IP) research perspective and entails structuring practice of a number of movement tasks that need distinctly different motor programs (relative force and timing of muscle contractions) by manipulating levels of intra and inter-task interference created by different practice schedules.
A low CI practice schedule would be ‘blocked practice’, where the same skill is executed over and over again. With blocked practice, there is no interference from having to re-organise movement coordination from a different movement pattern between subsequent attempts. This allows learners to execute and adapt one movement coordination pattern until they are able to perform it.
From an information processing perspective, this is supposed to allow the repetition of a solution. In most studies, this is associated with higher performance outcomes in the practice session.
Medium CI includes ‘serial practice’ schedules (like on the water circuits) where skills that are likely to be performed by being linked together, are practiced linked together where they can be anticipated in advance. Serial practice schedules allow the opportunity to pre-plan, repeat, compare and reflect on subsequent attempts whilst maintaining practice conditions that are adaptive and realistic.
High CI is ‘random practice’ where there is no opportunity to plan or repeat and compare responses. It is worth mentioning that in reality there are unlikely to be any true random sports. There is always some element of reading and understanding the environment and context. High CI supports learning because it allows the development of quick decision-making and skillful execution of movement patterns linked to picking up perceptual information.
From an IP perspective, the solution has been forgotten and needs to be retrieved, leading to forgetting and retrieval and/or embellishment of the motor program. High CI is associated with low performance in practice but much better performance in retention and transfer tasks.
Obviously, from an ecological perspective, there are no motor programs and the advantages are more about supporting intention, focus of attention, and (re)calibration of perception and action. However, each individual may be experiencing totally different levels of variability in their performance and may need to increase or decrease complexity or variability in a way that is more individual than a structure of practice that makes everyone do the same things, in the same order, for the same number of repetitions.