I remember sitting in on a master class one summer in which my friend was playing for the Russian cellist Natalia Gutman. After he finished playing, she smiled, kind of chuckled a bit, and said a few words to her translator. Who explained that she thought he was playing his instrument completely wrong, but because he sounded so great, he should just keep doing what he was doing, and she had no desire to change anything about his technique.
Indeed, when you think about your favorite musicians (or athletes), don’t they all have a unique physical style and approach to playing? Like, if you could somehow turn Glenn Gould and Martha Argerich videos into stick figure videos for instance, it would still be pretty easy to identify which was which, right?
No one-size-fits-all?
Research on athletes suggests that not only do different individuals have different approaches to movement that enable them to achieve the same results, there’s actually a surprising amount of variability from one repetition to the next even for the same athlete. Meaning, they may never use the same exact combination of joint angles and force and acceleration from one repetition to the next, yet still consistently make the basket, hit the desired target, or throw the ball to the same point.
In much the same way that you could produce a consistently beautiful sound, note after note, but without using the same exact combination of bow weight, speed, point of contact, and number of bow hairs making contact with the string from one note to the next.
And this flexibility turns out to be quite important, because once you leave the practice room, you inevitably have to adapt to never-before-encountered situations on the fly, whether it’s the demands of an eccentric conductor, a hall’s quirky acoustics, or your excitable cellist’s spontaneous decision to take the fast movement a few clicks faster than they did in rehearsal.
The traditional approach…
But this flexibility, and the variability in mechanics that you see from one performer to the next is not really reflected in the traditional approach to learning. In that we all typically start out by learning how to perform a new skill in a very specific, prescribed way. As if there’s only one single correct way to perform the skill, and the key to success is lots and lots of perfect repetitions.
But if we all eventually end up deviating from this hypothetical ideal in some way or another, is the traditional “here’s-the-correct-way-to-perform-this-skill-so-do-a-bunch-of-repetitions-until-you-get-it-right” approach the best way to learn a skill? Or is there an alternative that might be better?
“Differential learning”
In the late 1990’s, German motor learning researcher Wolfgang Schöllhorn proposed something new. An approach that he called differential learning. Where instead of focusing on super consistent “perfect” repetitions of a skill with minimal variability from one repetition to the next, the idea is to encourage the learner to maximize variability from one repetition to the next. And to explore a much broader range of possible movement patterns, with little repetition of any one variation, in order to intuitively discover what works best for them. To basically allow the learner to do things in all the “wrong” ways as well as the “right” ways.
Like practicing a penalty kick in soccer with one eye closed. Or dribbling with your hands crossed over your chest.
Or for a young violin student, for instance, the traditional approach might be to encourage the student to keep the bow perfectly straight and follow a consistent path between the bridge and fingerboard every single time they practice their scales. Whereas the differential learning approach might be to encourage them to play close to the bridge, or over the finger board, or where the bow drifts further away from the bridge as they get closer to the tip, or with a funky bow grip of some kind, while standing on one leg, or with both eyes closed, etc. from one repetition of the scale to the next (while still trying one’s best to produce a beautiful sound, play in tune, etc.).
Which all sounds kind of fun…but what’s the point of this? What benefits does the differential approach have over the traditional method?
Let’s take a look!
A toothbrushing study
A group of 54 children, aged 6-9 years old, were recruited to participate in a toothbrushing study (Pabel et al., 2018).
Over the course of 15 days, a third of the students continued brushing like normal (control), while another third were given some training in the correct brushing technique and supervised by a dentist (traditional learning), and the final third were given the same training and a toothbrushing exercise to do selected randomly from a list (differential learning).
The exercises ranged from brushing their teeth with a 2kg weight on their wrist, or while sitting on an exercise ball, or with one eye covered, or with soccer goalie gloves on, or with their non-dominant hand, or with both hands at once, or in a different sequence than they were originally taught, etc.
And then they followed up with the kids at day 21, 42, and 63 to see if there were any changes to the buildup of plaque and propensity for bleeding compared with day 1.
And was there any difference between the groups?
Results
Yep!
The differential learning group had the lowest plaque scores at each of the follow-up measurements, and had significantly better results in both areas of dental health as compared with the control and traditional learning groups.
Ok, so these crazy variations might have helped with first and second-graders, but maybe this simply turned toothbrushing into more of a game, increasing their engagement in the task…
Is there any evidence that this helps with adults, doing something a little more serious?
Dental students
Well, sticking with the theme of dental health, a study of third-year dental surgery students (Pabel et al., 2017) found similar results.
In this study, 32 students were either taught how to prepare a partial crown through a traditional approach or through a differential learning approach.
The traditional approach involved a video demonstration, verbal instructions, lots of practice and repetition of the correct procedure, and verbal and written feedback by supervisors throughout learning. Whereas the differential approach involved the same video demonstration and verbal instructions, but no expert feedback, and a series of varying practice challenges instead of normal “perfect practice” and repetition.
Like the toothbrushing study, these variations included preparing the partial crown with a weight on one’s dominant hand, or while using the non-dominant hand, or with glasses reversed, or with the practice dummy head continuously moving, or with the dummy’s mouth partially closed, or while wearing earplugs, or with the dominant hand attached to a resistance band, etc.
And did one approach work any better than the other?
Results
Well, the students were tested twice on their ability to prepare a partial crown. The first test took place on the day right after they completed their training. And the second test took place 20 weeks later.
At the first test, the differential learning group performed slightly better, as 68% of those students passed the exam, while 54.3% of the traditional learning students also passed. But this difference wasn’t statistically significant, so when it comes to performance right after training, there may not be much of a difference between the two learning methods.
But when it was time for the second test, which is a better indicator of how much of what they learned in their training stuck, it was a different story. When tested several months after their training, the differential learning group performed waaay better, with a passing rate of 68.8% to 18.9% for the traditional learning group.
So what can we learn from these studies?
Caveats
Well, before we go into takeaways, it’s important to note that this is still a developing area of motor learning. There’s a lot of intriguing research here, with some cool findings in a range of different sports (it’s not just oral hygiene!), and a recent meta-analysis of the studies in this area did find that differential learning shows promise. But there are still a lot of questions that researchers are still exploring. For instance, it’s not really clear how much variability, or what type of variability is best, and when.
Schöllhorn has suggested that those with less experience, whose movements are still naturally pretty variable, would probably do best with smaller or less extreme types of variation at first. While those who are more skilled and already performing skills pretty consistently may benefit from exploring a broader and more extreme range of variations.
(And if you want to do a much deeper dive, check out this page where Arizona State University professor Rob Gray has curated tons more info on differential learning and provides four guidelines on how to implement this with students – located under the heading “So, how do I find the ‘optimal level of noise’ as a coach?”)
Takeaways
For me, there are a few main takeaways.
For one, I think it’s another reminder that the practice strategies that lead to the fastest improvements right this second, don’t necessarily translate into better learning, retention, and performance tomorrow.
But more than that, I like that the differential learning approach seems to destigmatize mistakes in the learning process. Like, instead of getting all tense and worrying about whether you are playing “correctly” or not, if the goal is to try a wide range of possibilities to discover what works best for you, there is no such thing as a mistake. There are simply approaches that work better and approaches that work less well, and exploring them all is part of the self-discovery process.
It also reminds me a lot of something that I read pianist Martin Krause had his students do. Specifically, he’d have them play their repertoire in ways that they would never dream of doing on stage. With vastly different articulations or dynamics that weren’t in the score, transposed in different keys, etc.
Kind of like the oddball putts that you see in this golf video: The best thing you can do for your putting
Whether you’re already doing something like differential learning in your practice or teaching, or are getting excited at the thought of trying a bit of this in the coming week, what differential learning variations – from subtle to crazy – might be fun to try, specific to your instrument? Playing piano while standing on one foot? Or timpani while sitting on an exercise ball with your eyes closed? Please share below in the comments!
References
Pabel, S. O., Freitag, F., Hrasky, V., Zapf, A., & Wiegand, A. (2018). Randomised controlled trial on differential learning of toothbrushing in 6- to 9-year-old children. Clinical Oral Investigations, 22(6), 2219–2228. https://doi.org/10.1007/s00784-017-2313-x
Pabel, S. O., Pabel, A. K., Schmickler, J., Schulz, X., & Wiegand, A. (2017). Impact of a Differential Learning Approach on Practical Exam Performance: A Controlled Study in a Preclinical Dental Course. Journal of Dental Education, 81(9), 1108–1113. https://doi.org/10.21815/jde.017.066
Tassignon, B., Verschueren, J., Baeyens, J. P., Benjaminse, A., Gokeler, A., Serrien, B., & Clijsen, R. (2021). An Exploratory Meta-Analytic Review on the Empirical Evidence of Differential Learning as an Enhanced Motor Learning Method. Frontiers in Psychology, 12. https://doi.org/10.3389/fpsyg.2021.533033
