The constant flux and caprice of mental events do not admit of the establishment of stable experimental conditions.

The constant flux and caprice of mental events do not admit of the establishment of stable experimental conditions.

Often, even after years, mental states once present in consciousness return to it with apparent spontaneity and without any act of the will; that is, they are reproduced involuntarily.

The school-boy doesnt force himself to learn his vocabularies and rules altogether at night, but knows that be must impress them again in the morning.

Humans 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.

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.

No matter how thoroughly a person may have learned the Greek alphabet, he will never be in a condition to repeat it backwards without further training.