Principles of Motor Learning Explained

The Principles of Motor Learning are a set of processes that facilitate the acquisition and retention of motor skills.

Motor Performance - The ability to perform a motor task.  How the movement is performed during training, within a structured session. (Temporary change during the speech session).
Motor Learning - Retention and generalization (transfer) of skills learned including how the movement is performed at another time or in another setting outside of speech therapy.  The process of the learner acquiring a skill and making a movement automatic.

Precursors to motor learning in young children:

1. Joint attention / Sustained Attention
2. Communicative Intent / Motivation
3. Ability to Imitate and pre-practice (including phonetic placement training)

Conditions of Practice

Target Choices/Target Complexity
(Type, length, phonetic complexity)

• Simple Task - Focuses on easier sounds and sequences (what the child can say or what is presumed easier and earlier developing)
• Complex Task - Including sound sequences with increased length and phonetic complexity that are more difficult

*Focus on phonemes already in a child’s repertoire as well syllable structures that he/she is already using and build off of that.

Practice Amount: Small vs Large
Refers to the amount of time spent practicing movements

• Large amount of practice - High number of practice trials
• Small amount of practice - Low number of practice trials

*Large amount of practice provides more opportunity to establish a motor plan.
*Maximum response trials - Attempt 50-200 trials depending on the severity of the disorder.
*Larger number of trials leads to greater retention and generalization (Edeal & Gildersleeve-Neumann, 2011).

Practice Distribution: Mass vs Distributed practice

• Massed practice - Practicing a given number of trials in a short period of time
• Distributed practice - Refers to how the practice is divided over time including spreading practice out over a longer period of time.  

*Massed practice is used to establish a motor plan.  It leads to quicker acquisition of a skill, however less generalization.
*Distributed practice leads to better retention and generalization of a skill (Bahrick & Hall, 2005).
*Typically in children with CAS, distributed practice over time (4 sessions a week for 20 minutes) appears to be more beneficial than massed practice (1x a week for an hour).
*Massed practice may look like working on 3 targets for 4 weeks, and then 3 novel targets for 4 weeks, rather than 6 targets for 8 weeks straight.
 
Practice Schedule: Blocked vs Random practice

• Blocked practice - Practice each stimuli in a block (e.g. you have 6 target words total and you practice target 1 10x, then move on to target 2 and practice 10x, target 3, etc)
• Random Practice – Mixing the practice of each stimuli once or twice across the whole set. Different movement targets are practiced in a random order (e.g. you have those same 6 target words, however you practice them in an unpredictable random order)

*Start with a more blocked practice for acquisition (Shea et al., 2001) then move to random as movement accuracy improves, so the child doesn’t over habituate.  
*Evidence shows random practice leads to better motor learning and generalization (Shea et al., 1990), but for more severe cases, blocked practice may be necessary at first to optimize learning. 
*If you start with random practice then it will take the child longer time to acquire the accurate movement gesture for that target. 
*One study in CAS treatment (~2.5hr tx/week, 2-4 week phases): 2 children showed greater retention with blocked, 1 child showed greater retention with random and 1 child showed no clear improvements with either condition (Maas & Farinella, 2012) .

Practice Variability: Constant vs Variable practice

• Constant practice - Practicing the same target, in the same context (i.e. /p/ in syllable initial position: pie, pa, pee, poe)
• Variable practice - Practicing various targets in different contexts (e.g. /p/ /k/ and /d/ in syllable initial and final position: pa, up, do, ick, key or the target word "do", changing contexts such as having the target word produced in different phrases ("I do", "do it!", "you do")

​*Variable practice is better for retention and facilitates motor learning (Shea et al, 2001).  Having some variability with target choices benefits speech motor learning.
*Constant practice is better for acquisition of a skill and may be better for learning the underlying timing pattern of a motor program (Lai et al., 2000).
*Variability can also include working on prosody to practice more flexibility in motor planning and programming as well changing stimuli (orthographic vs picture), changing carrier phrases or even changing the setting.  

Conditions of Feedback
(Type: Knowledge of Results/Knowledge of Performance, Frequency: High/Low, Timing: Immediate/Delayed)

Feedback Type: Knowledge of Results vs Performance

• Knowledge of Results - Information about the outcome that is binary. You tell the client if they achieved the target or did not. (e.g. saying “good job” or “that’s not right”)
• Knowledge of Performance - Giving more specific feedback regarding the movement performance (e.g. “I like how you pushed your lips out” or "Your jaw needs to open a little more")

*Knowledge of performance has proven to be better with more complex tasks where the goal is unknown or the client does not have the knowledge of how to reach the goal (Newell et al., 1990).  So for early acquisition of a motor skills, begin with knowledge of performance.
*To promote generalization and retention of a motor skill, move to knowledge of results feedback.

Feedback Frequency: High vs Low 

• High - Feedback after every attempt at production regardless of accuracy 
• Low - Feedback only after some attempts at production regardless of accuracy

*Low frequency feedback has been shown to benefit learning (Bruechert et al., 2003) and promotes retention of a skill.
*More frequent feedback might be required initially for learning of complex skills. Begin with more feedback and gradually fade to less, so a child does not rely on this.
*Children may benefit more from more high frequency feedback overall (Sullivan et al., 2008).
*Few studies have examined feedback frequency in speech motor learning.  *One study with children with CAS (Maas, Butalla & Farinella, 2012) showed 2 children with greater retention with low frequency feedback, 1 child with greater retention with high frequency feedback and 1 child with no improvement in either condition. (High frequency feedback meaning feedback given on 100% of trials, low frequency feedback meaning feedback given on 60% of trials).

Feedback Timing: Immediate vs Delayed

• Immediate - Feedback immediately following attempt at production
• Delayed - Feedback provided with a delay (e.g. 5 seconds)

*Delayed feedback enhances learning compared to immediate feedback (Vander Linden et al., 1993, Strand et al., 2006).

References: Maas. et al. (2008). Principles of Motor Learning in Treatment of Motor Speech Disorders. American Journal of Speech-Language Pathology, 17, 277-298.