Spacing effect

The spacing effect is the phenomenon whereby learning is greater when studying is spread out over time, as opposed to studying the same amount of content in a single session. That is, it is better to use spaced presentation rather than massed presentation. Practically, 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 in a longer time frame. Important to note, however, is that the benefit of spaced presentations does not appear at short retention intervals, in which massed presentations tend to lead to better memory performance. This effect is a desirable difficulty; it challenges the learner but leads to better learning in the long-run.

The phenomenon was first identified by Hermann Ebbinghaus, and his detailed study of it was published in the 1885 book Über das Gedächtnis. Untersuchungen zur experimentellen Psychologie (Memory: A Contribution to Experimental Psychology). This robust finding has been supported by studies of many explicit memory tasks such as free recall, recognition, cued-recall, and frequency estimation (for reviews see Crowder 1976; Greene, 1989).

Researchers have offered several possible explanations of the spacing effect, and much research has been conducted that supports its impact on recall. In spite of these findings, the robustness of this phenomenon and its resistance to experimental manipulation have made empirical testing of its parameters difficult.

Decades of research on memory and recall have produced many different theories and findings on the spacing effect. In a study conducted by Cepeda et al. (2006) participants who used spaced practice on memory tasks outperformed those using massed practice in 259 out of 271 cases.

As different studies support different aspects of this effect, some now believe that an appropriate account should be multifactorial, and at present, different mechanisms are invoked to account for the spacing effect in free recall and in explicit cued-memory tasks.

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