Procedural memory is a type of implicit memory (unconscious, long-term memory) which aids the performance of particular types of tasks without conscious awareness of these previous experiences.
Procedural memory guides the processes we perform, and most frequently resides below the level of conscious awareness. When needed, procedural memories are automatically retrieved and utilized for execution of the integrated procedures involved in both cognitive and motor skills, from tying shoes, to reading, to flying an airplane. Procedural memories are accessed and used without the need for conscious control or attention.
Procedural memory is created through procedural learning, or repeating a complex activity over and over again until all of the relevant neural systems work together to automatically produce the activity. Implicit procedural learning is essential for the development of any motor skill or cognitive activity.
History The difference between procedural and declarative memory systems were first explored and understood with simple semantics. Psychologists and philosophers began writing about memory over two centuries ago. "Mechanical memory" was first noted in 1804 by Maine de Biran. William James, within his famous book: The Principles of Psychology (1890), suggested that there was a difference between memory and habit. Cognitive psychology disregarded the influence of learning on memory systems in its early years, and this greatly limited the research conducted in procedural learning up until the 20th century. The turn of the century brought a clearer understanding of the functions and structures involved in procedural memory acquisition, storage, and retrieval processes.
McDougall (1923) first made the distinction between explicit and implicit memory. In the 1970s procedural and declarative knowledge was distinguished in literature on artificial intelligence. Studies in the 1970s divided and moved towards two areas of work: one focusing on animal studies and the other to amnesic patients. The first convincing experimental evidence for a dissociation between declarative memory ("knowing what") and non-declarative or procedural ("knowing how") memory was from Milner (1962), by demonstrating that a severely amnesic patient, Henry Molaison, formerly known as patient H.M., could learn a hand–eye coordination skill (mirror drawing) in the absence of any memory of having practiced the task before. Although this finding indicated that memory was not made up of a single system positioned in one place in the brain, at the time, others agreed that motor skills are likely a special case that represented a less cognitive form of memory. However, by refining and improving experimental measures, there has been extensive research using amnesic patients with varying locations and degrees of structural damage. Increased work with amnesic patients led to the finding that they were able to retain and learn tasks other than motor skills. However, these findings had shortcomings in how they were perceived as amnesic patients sometimes fell short on normal levels of performance and therefore amnesia was viewed as strictly a retrieval deficit. Further studies with amnesic patients found a larger domain of normally functioning memory for skill abilities. For example, using a mirror reading task, amnesic patients showed performance at a normal rate, even though they are unable to remember some of the words that they were reading. In the 1980s much was discovered about the anatomy physiology of the mechanisms involved in procedural memory. The cerebellum, hippocampus, neostriatum, and basal ganglia were identified as being involved in memory acquisition tasks.
Working memory Models of working memory primarily focused on declarative memory until Oberauer suggested that declarative and procedural memory may be processed differently in working memory. The working memory model is thought to be divided into two subcomponents; one is responsible for declarative, while the other represents procedural memory. These two subsections are considered to be largely independent of each other. It has also been determined that the process for selection may be very similar in nature when considering either modality of working memory.
Acquisition of skill The acquisition of skill requires practice. Merely repeating a task alone, however, does not ensure the acquisition of a skill. Skill acquisition is achieved when an observed behaviour has changed due to experience or practice. This is known as learning and is not directly observable.Zimbardo, P. G., and Gerring, R. J. (1999). Psychology and life. (15th ed.). New York: Longman. The information processing model, which incorporates this idea of experience, proposes that skills develop from the interaction of four components central to information processing. These components include: processing speed, the rate at which information is processed in our processing system; breadth of declarative knowledge, the size of an individual's factual information store; breadth of procedural skill, the ability to perform the actual skill; and processing capacity, synonymous with working memory. The processing capacity is of importance to procedural memory because through the process of proceduralization an individual stores procedural memory. This improves skill usage by linking environmental cues with appropriate responses.
One model for understanding skill acquisition was proposed by Fitts (1954) and his colleagues. This model proposed the idea that learning was possible through the completion of various stages. The stages involved include: Cognitive phaseFitts, P. M., Posner, M. I. (1967). Human Performance. Belmont, CA: Brooks/Cole Associative phase Autonomous phase (also called the procedural phase)
Cognitive phase
At this point in Fitts' (1954) model of skill acquisition individuals come to understand what an observed skill is composed of. Attention at this point in the process is significant for the acquisition of skill. This process involves breaking down the desired skill to be learned into parts and understanding how these parts come together as a whole for the correct performance of the task. The way an individual organizes these parts is known as schemas. Schemas are important in directing the acquisition process and the way an individual comes to choose schemas is described by metacognition.
Associative phase The associative phase of the Fitts (1954) model involves individuals repeated practice until patterns of responding emerge. At this part in the model, actions of the skill become learned (or automated) as ineffective actions are dropped. An individual's sensory system acquires the accurate spatial and symbolic data required for the completion of the skill. The ability to differentiate important from unimportant stimuli is crucial at this stage of the model. It is held that the greater the amount of important stimuli associated with a task, the longer it will take to complete this phase of the model.
Autonomous phase This is the final phase in Fitts' (1954) model, and it involves perfecting skill acquisition. The ability to discriminate important from unimportant stimuli are made quicker and less thought process is required because the skill has become automated. Important to this phase of the model is experience and factual knowledge store for the observed skill.
Alternative view: the "predictive cycle" Another model for understanding skill acquisition through procedural memory has been proposed by Tadlock (2005).Tadlock, D.: Read Right! Coaching Your Child to Excellence in Reading by Dee Tadlock, Ph.D. New York: McGraw-Hill, 2005 The model is significantly different from Fitts' 1954 view in that it does not require conscious understanding of a skill's components. Rather, the learner is only required to maintain in conscious awareness a concept of the desired result. Tadlock has applied the view successfully to reading remediation (Scott et al., 2010Scott, C. et al.: Evaluation of Read Right in Omaha Middle and High Schools 2009–2010 by C. Scott, K. Nelsestuen, E. Autio, T. Deussen, M. Hanita). The stages involved include: Attempt Fail Implicitly analyze the result Implicitly decide how to change the next attempt so that success is achieved The stages are repeated over and over until the learner builds or remodels the neural network to guide an activity appropriately and accurately without conscious thought. The context for this view is similar to how physical therapy works to help brain-injured patients recover lost functions. The patient maintains the desired result (e.g., control over hand movement) while making repeated attempts, without conscious awareness of the neural activity required to make the hand move. The patient continues to make attempts until movement is achieved. In the case of brain injury, how much progress is made depends upon the extent of the injury and the "mental force" or "will power" applied by the individual. Most individuals with reading problems have brains unaffected by brain injury, but negatively affected by an undefined problem with early learning in the area of reading. Because the brain is otherwise healthy, Tadlock has used highly structured methods associated with the Predictive Cycle to successfully remediate individuals with mild to severe reading problems (including dyslexia).
Practice and the power law of learning Practice can be an effective way to learn new skills if knowledge of the result, more commonly known as feedback, is involved. There is an observed phenomenon known as the power law of learning, which predicts the rate of skill acquisition over practice time. The power law of learning says that learning occurs at the fastest rate in the beginning then drastically tapers off. The rate at which practice loses its ability to sharpen execution is independent from the skill being practiced and the type of animal learning the skill. For example, participants in a reading speed study made the greatest leap in the first days of the experiment, while additional days of practice saw only slight improvement.
The power law of learning can be overcome if the subject is shown a more effective way to accomplish the task. A study subject was shown a film comparing his task performance, kicking a target as rapidly as possible, with that of a known way of minimizing kicking time. Though the subject had reached the limit of his ability to improve through practice as predicted by the power law of learning, viewing the film resulted in a breakthrough in his ability that defied the power law of learning. Viewing the film is an example of observational learning, which effectively gives the viewer new memories of a technique to draw upon for his or her future performances of the task.
Tests Pursuit rotor task A device used to study visual-motor tracking skills and hand–eye coordination by requiring the participant to follow a moving object with a cursor or use a stylus to follow the target on a computer screen or a turntable. With the computer screen version, the participant follows a dot on a circular path like the one shown below.
The pursuit rotor task is a simple pure visual-motor tracking test that has consistent results within age groups. This displays a measurement of procedural memory as well as demonstrates the participant's fine motor skills. The pursuit rotor task tests the fine-motor skills which are controlled by the motor cortex illustrated by the green section below. The results are then calculated by the participant's time-on and time-off the object. Amnesic participants show no impairment in this motor task when tested at later trials. It does however seem to be affected by lack of sleep and drug use.
Serial reaction time task