Monday, 14 November 2016

Multiple Rhythm Skills

Figure from Tierney & Kraus, 2015.

It’s a rainy Monday night and I’m giving Nicola her weekly lesson on the grand piano in the sanctuary of the church.  She’s a reticent girl with an engaging, shy smile, who practices consistently and plays well.  In particular, she has an impeccable sense of rhythm, always performing her pieces with accurate and consistent timing. 

Nicola is working towards her RCM Grade 4 exam, so we take some time in the lesson to practice for the ear-training requirements she will face.  She correctly names intervals and chord qualities as I play them, and flawlessly copies back a short melody at the keyboard.  But when I turn to the rhythm clap-backs, her face falls and she gets a worried wrinkle in her forehead.  We both know that this is her weak spot.  I count in and then play a three-bar melody for her, emphasizing the strong beats to help her maintain a sense of meter.  I encourage her to tap along silently as I play the tune a second time.  Then it’s her turn to clap the rhythm back to me.  She claps the first measure correctly, but falters in the second measure and just stops.  She clearly has no idea what comes next.

I never could quite make sense of why this is so difficult for her.  Her sense of rhythm is fantastic, but clap-backs stump her every time.  She just can’t keep the rhythm in her head long enough to clap it back.  So when I saw a research paper entitled “Evidence for Multiple Rhythmic Skills”, I immediately thought of Nicola and was drawn in.

The paper, published in PLOS ONE in 2015, comes from the lab of Nina Kraus, who has done a lot of work looking at how musical training affects language development in children, and in particular how it affects reading skills.  Research has shown a link between rhythm skills and reading ability, and so it seems like it would be important to understand what we mean by “rhythm skills”.  Are all rhythm-related abilities grouped together in the brain so that if you’re good at one rhythm task you’ll be good at another?  Or can rhythm skills be divided into different groups that rely on different brain networks?

To answer these questions, Tierney and Kraus tested 67 volunteers on four different rhythm tasks.  In the first, the volunteers simply had to tap along (on a conga drum) to a metronome, and the researchers kept track of how closely the tapping matched the metronome.  In the second task, the volunteers again had to tap to a metronome, but this time the tempo was variable, so they had to adjust their tapping to the changing speeds.  In the third task, the volunteers were presented with a repeating rhythm, and had pick up the rhythm and tap along with it.  And the fourth task was similar to the rhythm clap-backs my students have to do:  the volunteers heard a rhythm and had to tap it back.

The researchers looked for correlations between the tasks.  If people’s performance on two tasks is correlated, it means that when people are good at one, they are usually good at the other. The researchers present this type of data as a scatterplot, with each dot representing the performance of an individual person.  If the points are fit by a diagonal line, this shows a positive correlation.

Figure from Tierney & Kraus, 2015

It turns out (as you can see in the figure above) that performance on the metronome tapping and tempo adaptation tasks was correlated.  The researchers conclude these are both based on the same skill of beat tapping.  The third and fourth task, tapping along to rhythms and remembering rhythms were also correlated, both based on rhythm memory skill.  But there wasn’t any real correlation between the two groups of tasks.

The researchers state their conclusions pretty clearly:  These results support the theory that there are multiple dissociable rhythm skills, but do not support the existence of a single overarching rhythmic competence or ‘rhythm IQ’.”

This means that it’s actually completely reasonable for Nicola to have a good sense of beat and to be able to play rhythms well in her pieces, but have problems with rhythmic memory.  The two are based on completely different rhythm skills.  And what that means for me as her teacher is that I need to focus on practicing musical memory with her, and not try to improve her clap-backs by working on other types of rhythm tasks.  It’s a mistake for me to think of rhythm as one thing, and then just have in mind that Nicola needs help with rhythm, when in fact most of her rhythm skills are excellent.  So I’ll be working specifically on rhythm memory with her – practicing formal clap-backs as well as simple “repeat after me” exercises, and looking for patterns in the rhythms that she can grab on to.