Hermann Ebbinghaus

“ 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. But if he chances to set out purposely to learn it backwards, he will probably accomplish this in noticeably shorter time than was the case in the previous learning in the customary order. ”

“ The ideas which are conceived in one act of consciousness are, it is true, all bound together, but not in the same way. The strength of the union is, rather, a decreasing function of the time or of the number of intervening members. It is therefore smaller in proportion as the interval which separates the individual members is greater. Let a, b, c, d be a series which has been presented in a single conscious act, then the connection of a with b is stronger than that of a with the later c ”

“ One needs but to say that, in the case of an unfamiliar sequence of syllables, only about seven can be grasped in one act, but that with frequent repetition and gradually increasing familiarity with the series this capacity of consciousness may be increased. ”

“ This form of non-voluntary reproduction is one of the best verified and most abundantly established facts in the whole realm of mental events. It permeates inseparably every form of reproduction, even the so-called voluntary form. ”

“ But it is clearly quite idle to contend about the matter if observation is limited to conscious mental life, to the registration of that which whirls around by chance on the surface of the sea of life. ”

“ Let a series, a, b, c, d... be given in perception, then a, from the very first moment of the perception and during its continuance, is subjected to inhibition by other ideas present in consciousness. While a, already partially withdrawn from full consciousness, is more and more inhibited, b comes up. ”

“ If on the other hand in the first learning threads of association are spun not merely from each member to its immediate successor but also over intervening members to more distant syllables, there would exist, already formed, certain predispositions for the new series. The syllables now in succession have already been bound together secretly with threads of a certain strength. In the learning of such a series it will be revealed that noticeably less work is required than for the learning of an altogether new series. ”

“ One side call attention to the undoubted fact that in spite of complete mastery of, say, the Greek alphabet a person is not at all in a position to repeat it readily backwards if he has not specially studied and practiced it in this form. ”

“ On the basis of our present knowledge neither the one nor the other of these possibilities can be declared self-evident
To facilitate an insight into the actual conditions I have instituted a few preliminary experiments in the following way. Six aeries of 16 syllables each were impressed upon the memory by a 16- or 64-fold attentive repetition. After 24 hours an equal number of derived series of the same length, which had been obtained from those already learned by skipping one intermediate syllable, were learned by heart to the first repetition. ”

“ The function of the conscious will, for example, in all the numerous reproductions of the syllable-series which we have come to know, is limited to the general purpose of reproduction and to laying hold of the first member of the series. ”

“ As we now know, the directness or indirectness of the sequence is without effect upon the general nature of what happens between ideas which succeed each other. In both cases connections are formed which on account of their complete similarity can be designated only by the common term, Association. But these are of different strength. As the succession of united ideas approaches ideal immediacy the connecting threads grow stronger, and in proportion as it departs from this ideal, these threads grow weaker. ”

“ If the number of repetitions is made greater, will the threads of separate strength, which bind together all the members of a series learned by heart, increase in strength in the same proportion? Or is the nature and rate of their increase in strength a different one as is the case with the strength of the threads themselves? ”

“ It is so significant, and at the same time the decrease in the after-effect of connections which were formed over 2, 3, 7 intervening members is so gradual a one, that the assertion can be made, am these grounds alone, that even the terms which stand still further from one another may have been bound to each other subconsciously by threads of noticeable strength at the time of the learning of the series. ”

“ Ideas which have been developed simultaneously or in immediate succession in the same mind mutually reproduce each other, and do this with greater ease in the direction of the original succession and with a certainty proportional to the frequency with which they were together. ”

“ So, for example, a series of 16 syllables, which have been thoroughly memorised, may be present in a single conscious act. Accordingly this “explanation” is freely available. Those for whom it was of value in the case of association by simultaneity or immediate succession can employ it fully as well for our case of indirect sequence. ”

“ For the more distant members of the original series they are weaker than for the nearer; for specific distances backwards they are weaker than for the same distances forward. The strength of all the connections increases as the number of repetitions increases. But the originally stronger threads between the nearer members are strengthened considerably more quickly than the weaker ones which connect the more distant terms. The more, therefore, the number of repetitions increases, the stronger, both absolutely and relatively, become the connections between immediately successive terms. ”

“ There remains, accordingly, a certain probability for the third possibility, namely, that the contrasting character of the average differences has in part at least an objective basis, that the more rapid learning of the derived series, II, IV, VI, was in part due to their manner of derivation. ”

“ Considering the close proportion which exists between the number of repetitions on a given day and the saving of work on the next, it cannot much matter whether the series were repeated, each 32 times, or were memorised each to the first possible reproduction. ”

“ It is possible that both influences were at work simultaneously so that the first experiments gave results which were somewhat too high; and the second, results that were somewhat too low. It is allowable, under this hypothesis, to put the two sets of figures together so that the contrasting errors may compensate each other. In this way there was finally obtained out of the 85 double tests the following table. ”