Time pilot

There was an aspect I omitted from my previous post, Space invaders, in which I covered the spacing effect as a means of maximising long-term retention.

Zsolt Olah picked it: interleaving and – ironically! – I judged it a bridge too far to include in the same post and so decided to split it out across a second one.

You’ll see why…

Interleaving

Before defining interleaving, I feel it’s helpful to review the opposite: blocked presentation or blocking. This approach is equivalent to massed presentation whereby the content is consumed successively:

An alternative approach is to split each block into leaves and vary their presentation. This approach is known as interleaved presentation or varied presentation or mixed presentation:

The illustration above maintains the topical sequence, in contrast to random interleaved presentation whereby the sequence is shuffled:

Spaced interleaving

Just as the spacing effect can be employed to produce spaced block presentation:

…so too can it be employed to produce spaced interleaved presentation (grouped):

…or spaced random interleaved presentation (grouped):

I use the qualifier “grouped” because, while that’s the traditional way of illustrating interleaving – I suspect due to the formal paradigm of education by which you fill up the periods assigned to you – I see no reason why each leaf couldn’t be separated over time; hence spaced interleaved presentation (separated):

…and spaced random interleaved presentation (separated):

As you can see, it gets complicated real quick, and that’s before employing reinforcement or the testing effect!

Dynamic interleaving

When I look at the various permutations of spacing and interleaving, I wonder if an optimal timing or sequencing regime exists. Full disclosure: I’ve done zero research to find out; if you have, I’d love to play my lazy web card and ask you to share your findings via a comment below.

I also wonder about the efficacy of a bespoke regime that sequences the leaves according to a dynamic pattern – test latest > test previous > present new – leading to a final summative test:

I call this regime spaced dynamic interleaved retrieval (quite a mouthful!) or dynamic interleaving for short. Again, if you’re aware of anything out there that’s similar, please let me know.