I say, may also claim a place in the complicated mechanism of these possible influences.
Section 15. Measurement of Work Required
The number of repetitions which were necessary for memorising a series up to the first possible reproduction was not originally determined by counting, but indirectly by measuring in seconds the time that was required to memorise it. My purpose was in this way to avoid the distraction necessarily connected with counting; and I could assume that there was a proportional relation existing between the times and the number of repetitions occurring at any time in a definite rhythm. We could scarcely expect this proportionality to be perfect, since, when only the time is measured, the moments of hesitation and reflection are included, which is not true when the repetitions are counted. Difficult series in which hesitation will occur relatively more frequently, will, by the method of time measurement, get comparatively greater numbers, the easier series will get comparatively smaller numbers than when the repetitions are counted. But with larger groups of series a tolerably equal distribution of difficult and equal series may be taken for granted. Consequently the deviations from proportionality will compensate themselves in a similar manner in the case of each group.
When, for certain tests, the direct counting of the repetitions became necessary, I proceeded in the following manner. Little wooden buttons measuring about 14 mms. in diameter and 4 mms. at their greatest thickness were strung on a cord which would permit of easy displacement and yet heavy enough to prevent accidental slipping. Each tenth piece was black; the others had their natural color. During the memorisation the cord was held in the hand and at each new repetition a piece was displaced some centimeters from left to right. When the series could be recited, a glance at the cord, since it was divided into tens, was enough to ascertain the number of repetitions that had been necessary. The manipulation required so little attention that in the mean values of the time used (which was always tabulated at the same time) no lengthening could be noted as compared with earlier tests.
By means of this simultaneous measurement of time and repe-
