Nikolai Bernstein – Stages of motor learning
While Gentile’s two-stage model continues to be used today, many skill acquisition specialists now advocate for the lost treasure of Nikolai Bernstein, who described the learning process as below.
- First Phase: Solving a motor problem, what level takes the leading role?
- Second Phase: Developing a motor representation or strategy to approach the problem.
- Third Phase: Identifying the most appropriate sensory corrections.
- Fourth Phase: Corrections are handed to the background level and are engaged without conscious awareness.
- Fifth Phase: Standardisation
- Sixth Phase: Stabilisation
Bernstein  quickly argued that skill acquisition begins by solving a motor problem, highlighting the term “problem”, thereby providing a comprehensive description of how difficult skill acquisition really is. Think about your house key, the only way your door is going to open is if that key fits perfectly into that lock. However, in process of doing this, you have to take the key out of your pocket, through space, into the keyhole, and only through a process of grip precision and rotation will your door open.
To break this down even further, the only way you learn this task is from accumulating experience growing up where you reached for your mother’s cheek, grabbed the toy off the table, put blocks into your playpen, and so on. Bernstein creatively simplified this through four levels. First, there is a leading level, the level of actions (level D) which is responsible for planning and exercising control. Then comes the older evolutionary levels which provide mechanisms for constructing movement. Bernstein put it simply as “coordinating movements with external space (level C), organising muscular synergies (level B), and regulating muscle tone (level A). “Repetition without repetition” as famously stated by Bernstein himself reminds us that no two movement patterns will ever be the same. Therefore, it is imperative not to engage in rote, repetitive practice when the idea of transfer engages variable, complex, and cognitive situations – this is done through varying parameters of each level.
It is important to think about how we’ve evolved as humans, essentially dating back to the prehistoric era where knuckle walking was the rarest form of locomotion presented by our ancestors, and many years later, we figured out how to walk upright due to a complex interaction of all the levels and the environment.
Another example is: If it wasn’t for level A, how did a frog learn to come out of the water to walk and jump? In fact, when learning how to serve a volleyball, coaches start from level A and work their way up to level D after a certain period of practice and drills. The best part is that what we learn at these levels translate to other tasks (e.g. a volleyball serve mimics a baseball throw).
The second phase is developing a strategy to approach the problem. This can be related back to Fitts and Posner’s  ‘cognitive stage’, where the learner is figuring out how to achieve the task goal. According to Bernstein, the learner recruits and assigns roles to the lower levels. For example, what muscles and how much of the muscle contraction capability will be recruited. If you are being chased by a rattlesnake, there will clearly be more muscle contraction than if you are running a lap around your local track. Either way, you are still engaging in the motor skill of running, but with different task goals.
The third phase is identifying the most appropriate sensory corrections. This phase is important because the learner should know how the skill feels. More importantly, how does the skill feel in different contexts? In a nutshell, these initial stages are planning stages where we are cautiously building the boundaries in which this action will take place. The fourth phase is when the corrections are handed to the background levels without conscious awareness – this is what the “ah ha” moment looks like 
One thing that separates Bernstein from the others is the role of sensory corrections  as stated above, shedding light to automatic feedback control. Think about how easy it is for you now to take a key out of your pocket and open your door. Many researchers allude to this as the movement strategy.
Thus far, we have built an orchestra, where all the components have learned their part. Now, we are ready to rehearse as a full orchestra. Harmony, standardisation, and stabilisation are key components to the final phase in this model. The learner is able to counteract external perturbations and disruptions that prevent the skill from being de-automatised. To solve a motor problem consistently under a variety of conditions, the learner must experience as many modifications of the task as possible, a form of repetition without repetition .
Let’s add a glove on your hand during a massive snowstorm. The task of opening the door with a key becomes a bit different than before. Think about post-ACL reconstruction where the ACL is back, but now it is about teaching it how to function with the rest of the body in different conditions. In conclusion, Bernstein states in his book, Dexterity and its Development , “The point is that during a correctly organized exercise, a student is repeating many times, not the means for solving a given motor problem, but the process of its solution, the changing and improving of the means (p. 205).”