Memory vs Time Graphs

by Justin Skycak on

A way to visualize some cognitive learning strategies.

Some cognitive learning strategies can be understood best by visualizing them on graphs of memory vs time.

Consider “spaced repetition,” a systematic way of reviewing previously-learned material. A “repetition” is a successful review at the appropriate time.


After each repetition, your memory begins to decay. But the more repetitions you complete on the same material, the slower your memory decays, and the longer you can wait until the next repetition.

“Interleaving” can be visualized on a similar type of graph. It’s helpful to see interleaving in contrast to the opposite strategy, “blocked practice,” which is far less efficient than interleaving.

Most traditional classrooms use blocked practice. But blocked practice is very inefficient because after you solve a handful of problems and reach a minimum effective dose, further practice offers diminishing returns.

Instead, it would be far more effective to spread problems across a broad mix of topics that you’ve previously learned. This is called interleaving.

To visualize interleaving vs blocked practice on a graph, we can consider the effect of a minimal dose (4 problems) on 5 different topics vs an excessive dose (20 problems) on a single topic.


Interleaving allows us to elevate many different memory curves with the same amount of work, not just one!