Hermann Ebbinghaus, answered from the texts and cited to the page.
To study the formation of a memory in its purity, I had to escape the influence of meaning. Ordinary material — words, verses, prose — is shot through with associations, interest, and prior knowledge that make one passage easy and another hard for reasons that have nothing to do with memory as such; if I learned poetry, I should be measuring not memory but my acquaintance with the poem.
So I built a material as nearly meaningless and uniform as I could: the nonsense syllable, by which every item is, so far as possible, equally new and equally indifferent, so that what I measure is the pure work of forming and retaining a fresh association.1 It is an artificial material, I grant it freely; I chose it precisely for its artificiality, as the physicist studies motion on a frictionless plane he will never find in nature.
One does not object to the frictionless plane that roads have friction. To isolate a process you must strip away what confounds it, even at the cost of naturalness — and then, the law once found in the pure case, restore the complications one by one.234
It even appears from this point of view as if the differences between sense and nonsense material were not nearly so great as one would be inclined a priori to imagine.Memory A Contribution to Experimental Psychology
For the same reason I refrained from the use of other foreign sounds although I tried at first to use them for the sake of enriching the material.Memory A Contribution to Experimental Psychology
In particular the activity immediately preceding the test was kept as constant in character as was possible. Since the mental as well as the physical condition of man is subject to an evident periodicity of 24 hours, it was taken for granted that like experi- mental conditions are obtainable only at like times of day^.Memory A Contribution to Experimental Psychology
To facilitate this acquaintance is the purpose of this translation. The translators wish to acknowledge their indebtedness to Professors Edward L. Thorndike, Robert S. Woodworth, and E. W. Bagster-Collins of Columbia University, to Professor Walter Dill Scott of Northwestern University and to Mrs. H. A. Ruger for assistance in revising manuscript and proof.Memory A Contribution to Experimental Psychology
The nonsense-syllable method is the most debated feature of Ebbinghaus's work, and the debate is methodological, not moral. Frederic Bartlett's Remembering (1932) mounted the classic critique: by studying only meaningless material Ebbinghaus isolated an artificial laboratory memory and left out the meaningful, reconstructive, schema-driven, and social remembering that is memory in real life; Bartlett's own studies of memory for stories showed it to be constructive and distorting, not a faithful savings-trace. The Gestaltists similarly objected to the atomism of associating meaningless elements. The modern verdict grants both: Ebbinghaus's controlled method yields robust, general laws (forgetting, spacing) precisely because it strips confounds, while Bartlett opened the complementary and equally necessary study of meaningful memory; the two traditions are now integrated rather than opposed. The "frictionless plane" defense is largely accepted for what the method was designed to do.