Spaced Repetition: Why Distributed Practice Beats Cramming

One of the oldest findings in experimental psychology is also one of the most useful, and it is still routinely ignored.

The spacing effect

Distributing study across separated sessions produces better long-term retention than massing the same total study time together. This was documented in the nineteenth century and has been replicated continuously since across material types and populations. Cramming produces better performance on an immediate test and substantially worse performance on a delayed one, which is precisely why it survives as a strategy despite being the wrong one for anything you need to keep.

Why it works

Competing explanations. The encoding variability account holds that studying in different contexts creates more retrieval routes. The study-phase retrieval account holds that each spaced repetition requires partially retrieving the earlier trace, and that retrieval is what strengthens it. The deficient processing account holds that massed repetitions are processed shallowly because the material still feels familiar. These are not mutually exclusive.

Scheduling it

Expanding intervals - reviewing after a day, then three days, then a week, then a month - are the standard approach, and spaced repetition software automates the scheduling based on how well you recalled each item. You do not need software: a simple system of reviewing new material the next day, the following week and the following month captures most of the benefit. The general principle is that the optimal gap scales with how long you need to retain the material.

A note on Cognizil

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