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 CHAPTER IX

RETENTION AS A FUNCTION OF THE ORDER OF SUCCESSION OF THE MEMBERS OF THE SERIES

I shall now discuss a group of investigations made for the purpose of finding out the conditions of association. The results of these investigations are, it seems to me, theoretically of especial interest.

The non-voluntary re-emergence of mental images out of the darkness of memory into the light of consciousness takes place, as has already been mentioned, not at random and accidentally, but in certain regular forms in accordance with the so-called laws of association. General knowledge concerning these laws is as old as psychology itself, but on the other hand a more precise formulation of them has remained—characteristically enough—a matter of dispute up to the very present. Every new presentation starts out with a reinterpretation of the contents of a few lines from Aristotle, and according to the condition of our knowledge it is necessary so to do.

Of these “Laws,” now—if, in accordance with usage and it is to be hoped in anticipation of the future, the use of so lofty a term is permitted in connection with formulae of so vague a character—of these laws, I say, there is one which has never been disputed or doubted. It is usually formulated as follows: 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.

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