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…

Aerobatic jets with coloured smoke trails.

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:

A pink block followed immediately by a blue block followed immediately by a green block.

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:

A pink leaf followed immediately by a blue leaf followed immediately by a green leaf, then another pink leaf followed immediately by another blue leaf followed immediately by another green leaf, then another pink leaf followed immediately by another blue leaf followed immediately by another green leaf.

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

A pink leaf followed immediately by a blue leaf followed immediately by a green leaf, then another blue leaf followed immediately by another green leaf followed immediately by another pink leaf, then another green leaf followed immediately by another blue leaf followed immediately by another pink leaf.

Spaced interleaving

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

A pink block flowing over time to a blue block flowing over time to a green block.

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

A pink leaf followed immediately by a blue leaf followed immediately by a green leaf, flowing over time to another pink leaf followed immediately by another blue leaf followed immediately by another green leaf, flowing over time to another pink leaf followed immediately by another blue leaf followed immediately by another green leaf.

…or spaced random interleaved presentation (grouped):

A pink leaf followed immediately by a blue leaf followed immediately by a green leaf, flowing over time to another blue leaf followed immediately by another pink leaf followed immediately by another green leaf, flowing over time to another green leaf followed immediately by another blue leaf followed immediately by another pink leaf.

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):

A pink leaf flowing over time to a blue leaf flowing over time to a green leaf flowing over time to another pink leaf flowing over time to another blue leaf flowing over time to another green leaf flowing over time to another pink leaf flowing over time to another blue leaf flowing over time to another green leaf.

…and spaced random interleaved presentation (separated):

A pink leaf flowing over time to a blue leaf flowing over time to a green leaf flowing over time to another blue leaf flowing over time to another green leaf flowing over time to another pink leaf flowing over time to another green leaf flowing over time to another blue leaf flowing over time to another pink leaf.

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

Ron Burgundy from Anchorman contemplating with a beer.

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:

A pink leaf flowing over time to a blue leaf flowing over time to a green leaf flowing over time to another blue leaf flowing over time to another green leaf flowing over time to another pink leaf flowing over time to another green leaf flowing over time to another blue leaf flowing over time to another pink leaf.

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.

A chart featuring Interleaving, within which is Spaced Interleaving, within which is Dynamic Interleaving.

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