Spacing effect

The spacing effect states that while you are more likely to remember material if exposed to it many times, you will be much more likely to remember it if the exposures are repeated over a longer span of time.

In other words, distributive repetition (presentations spread out over time) work better than massed repetition (presentations closely together in time).

There are two explanations for this finding. According to the deficient processing view, massed repetition leads to only one representation of the material in memory. However, according to the encoding variability view, distributed repetition is likely to entail some variability in presentation; this leads to a more robust memory that is more connected to other ideas.

For students, this effect suggests that "cramming" (intense, last-minute studying) the night before an exam is not likely to be as effective as studying at intervals over a much longer span of time.