A poem is learned by heart and then not again repeated. We will suppose that after a half year it has been forgotten: no effort of recollection is able to call it back again into consciousness.
Hermann EbbinghausOn the basis of the familiar experience that that which is learned with difficulty is better retained, it would have been safe to prophesy such an effect from the greater number of repetitions.
Hermann EbbinghausHumans more easily remember or learn items when they are studied a few times over a long period of time (spaced presentation), rather than studied repeatedly in a short period of time.
Hermann EbbinghausThe relation of repetitions for learning and for repeating English stanzas needs no amplification. These were learned by heart on the first day with less than half of the repetitions necessary for the shortest of the syllable series.
Hermann Ebbinghaus