The Spacing Effect

Which do you think would lead to better piano playing:  practicing one day a week for three hours or practicing 6 days a week for half an hour a day?  In both cases the total time spent practicing per week is the same (3 hours).  For most people, this is a no-brainer: we always suggest once-a-day practice.  It seems most logical to space out the practice sessions to once a day to promote better learning.  We know from experience that this works.

The Spacing Effect

There is a well-known psychological phenomenon called the Spacing Effect, where people learn better if learning sessions are distributed across time, compared to learning in one big massed session.  This was first shown in the late 1900’s, and has been extensively studied since then.

But why does it work? Why isn’t it just the total number of hours you spend learning something that determines how well you learn it?  There are a couple of different answers to this question.  The first is that fatigue and attention span limit the useful length of a practice session.  It’s just not reasonable to expect someone to practice for three hours solid and expect them to be putting in the same amount of mental and physical effort at the end that they were putting in at the beginning.  Also, there is evidence that when we are repeating something right away, we naturally do not pay as much attention the second time.  And, as I’ve discussed, attention is critical for learning

Spacing of Practice Promotes Synaptic Plasticity

The second, and perhaps more scientifically interesting answer, is that the physical processes in the brain that lead to learning seem more activated by spaced training sessions.  When we learn something, the connections between neurons, known as synapses, get stronger, making certain patterns of neuronal firing more likely to happen.  This synaptic plasticity involves cascades of chemical interactions between molecules in the synapse.  When we interrupt practice sessions with gaps, the chemical interactions are more strongly activated, making the synapse stronger.  From a psychological standpoint, the spacing effect works because retrieving a memory makes the memory stronger.

Optimal Spacing of Practice Sessions

Practicing once a day for 30 minutes definitely makes more sense than practicing once a week for 3 hours.  But would it be even better to practice twice a day for 15 minutes?  Or three times a day for 10 minutes each time?  What is the optimal spacing of our practice sessions?  I’m personally very curious about this, but there are no clear answers to these questions. However, it seems to me that the optimal length and spacing of practice sessions will be determined by the material that needs to be practiced.  A beginner student might benefit by practicing her short pieces in two-minute sessions, while an advanced student needs to spend more time at each practice session in order to really “get into” the practice and make some improvements. 

Rubin-Rabson (1940)

But I’d still really like to know if practicing twice a day would benefit musicians more than practicing once a day, even if the total time spent practicing were the same.  Is it better to have a night’s sleep between practice sessions, so sleep-dependent consolidation of the memory can occur? Or would it be better to practice in two or more sessions per day to try to maximize the spacing effect?  The only research paper I could find on this particular question was a study from 1940 by Rubin-Rabson.  In her study on memorization, experienced pianists practiced some pieces, either in one practice session, in two shorter practice sessions within one day, or in two short practice sessions over two days.  Which practice regimen led to better learning?  She tested this by having the pianists come back two weeks later and relearn the pieces.  Those who had practiced on two separate days had the easiest time relearning the pieces, those who practiced two sessions on one day were in the middle, and those who had used one massed practice session had the hardest time relearning.  The conclusion was that spacing out the practice sessions promoted better learning.

The spacing effect in daily practice

The problem with this study is that it is hard to apply the results to our regular daily practice.  How often do we learn a piece in one practice session and then have to play it two weeks later with no practice in between?  What I really want to know is if I should suggest to my students that they split their practice into two sessions per day, practicing each piece in both sessions.  My guess would be that their performance would improve more quickly.  Has anyone tried this?  I’d love to hear your comments.