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http://dx.doi.org/10.1037/12387-006
Retentiveness.—Retentiveness in some form is an indispensable condition of development or progress of any kind. Advance would be impossible unless the results of prior process persisted as the basis and starting-point of subsequent process. In marching, each step has its point of departure from the new position secured by the previous step. In marking time there is continual reversion to the same position and no advance. No house could be built if each brick vanished as it was laid, and had to be replaced anew. A rope cannot be formed of dry sand, which crumbles away as it is put together. Similarly, mental development would be impossible unless previous experience left behind it persistent after-effects to determine the nature and course of subsequent experience. These after-effects are called, in psychology, traces or dispositions, and the psychological law of retentiveness may be stated as follows: when and so far as mental development takes place through mental conditions, it does so because specific experiences leave behind them specific traces or dispositions, which determine the nature and course of subsequent process, so that when they are modified it is modified. (PsycINFO Database Record (c) 2017 APA, all rights reserved)