Jack A. Adams’ A Closed-Loop Theory Of Motor Learning attempts to explain the process of how motor learning is achieved in humans. He argues that a sufficient motor learning theory should cover how verbal and motor processes work together to produce learning and also how errors are detected and corrected. In this paper it will be shown that Adams fails to do this as there are numerous flaws incorporated into his argument. Adams tends to overlook necessary details and his theory fails to explain how motor learning is achieved in individuals who do not possess a “verbal capability”. The central components to Adams theory are the concepts of knowledge of results or KR, the perceptual trace, and the memory trace. In order to understand the flaws of Adams theory, a brief explanation of each is fundamental. According to Adams (1971,p. 122), KR is information about a movement’s error that is used to solve a problem. KR is the verbal component of Adams theory, which according to him, is key for motor learning to occur. Next, is his idea of the perceptual trace. According to Adams (1971, pg. 123) in order to move a limb, a reference of past movement is necessary (i.e. the perceptual trace), KR, and sensory feedback. The perceptual trace is almost the “memory” of past movement. It is weak in the beginning of a new movement, and strengthened as the number of correct trials increases. Adams asserts that KR is vital to forming a strong perceptual trace since KR gives information on error. However, once a strong perceptual trace is formed, KR can disappear since the trace is so strong. Once KR is withdrawn, Adams (1971, p.124) says, “ S can now learn without KR.” Finally, an explanation of the memory trace is needed. In order for a movement to actually begin, a memory trace is needed. According to Adams (1971, p 125) the memory trace is responsible for “selecting and initiating” the movement. As one is reviewing the components to Adams theory that I have outlined above, a major flaw is quick to reveal it self. Adams claims that knowledge of results is a key component to learning, however, there are many instances in life where motor learning can occur for simple self paced tasks with out KR. Yes, there is little doubt that KR will help one achieve desired results faster, but it must be possible to learn with out verbal knowledge of error. Small infants do it all the time, such as learning how to hold their own bottle, a task I would consider relatively simple. There are also other instances in life when KR is “unavailable” so to speak. The other counter arguments dealing with Adams theory are in regards to how feedback affects the PT and MT. It seems that Adams does not provide enough information as what happens when a completely foreign movement is being made. According to his theory, Adams claims that a memory trace starts the initial movement. The memory trace starts the movement but it is the perceptual trace that guides the movement. Where is the perceptual trace for a movement we have never done before, and how according to Adams theory, can we complete a movement if there is a non-existent perceptual trace? Regardless of KR, the perceptual trace has not even been formed yet. This leads me to question Adams theory; I feel that he did not pay attention to this detail, which is of utmost importance, being as though humans can learn how to do even relatively simple new motor movements all the time.

A third issue I find in Adams theory is that each single movement has its own separate perceptual trace and memory trace each stored in some special sort of memory device with in the central nervous system. This seems unrealistic. If humans had a distinct perceptual trace for each movement, how would be able to deviate from “strong” perceptual traces, and change simple movements as we are doing them? Also, no movement anyone makes is exactly the same. To have a separate perceptual trace and memory trace for every finite movement one is capable of making seems near impossible, and also very difficult to prove and test scientifically. Adams argument of forgetting must be void here because they made a very similar movement; perhaps they were off by just a couple mm in angle, something miniscule that changed everything. The point is no two movements are exactly alike. If each movement is slightly different than another yet you are trying to accomplish the same task, how is this similar but slightly different movement 1) not counted as error, and 2) wouldn’t each slight error, build a stronger perceptual trace for error? It seems as though Adams theory lacks how feedback mechanisms are able to adjust to a slight “error “after KR has been removed. Since his paper does not account for how learning is possible to occur with out KR, how completely new movements are formed in absence of a formed perceptual trace and memory trace, how a system with an infinite number of movements is able to be secretly stored in the CNS with out any detection, and finally his lack of explanation on how after KR is removed how adjustments are able to be made. Adams closed loop theory was a good place to start in the field, however, I feel its numerous flaws, and oversights are difficult to ignore.