Page:Memory (1913).djvu/127

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Retention as a Function of Order of Succession

119

1
A Sum of series (I, III, V)	B Sum of series (II, IV, VI)	Δ (B-A)
467	790	323
544	666	122
662	704	42
548	668	120
523	539	16
475	657	182
612	753	141
853	548	―305
637	641	4
499	780	281
m 582	675	93 P.E._m=±37

2
488	694	206
604	704	100
551	734	183
596	637	41
559	686	127
611	744	133
653	682	129
598	700	102
723	606	―117
643	678	35
m 603	687	84 P.E._m=±20

The sum of series II, IV and VI, found by averaging the ten experiments, is here in both cases, as can readily be seen, considerably greater than the sum of series I, III, V. The differences are, to be sure, of very different amounts for the separate experiments, and in one case they have a pronounced negative value; but these fluctuations are represented in the large probable error of the differences of the averages; and, in spite of the size of these errors, the positive character of the differences may be considered as fairly certain.

In all other investigated cases the following result appears: there are large fluctuations of the differences in the individual experiments, but a combination of the several experiments shows a decisive predominance for series II, IV, VI although the surplus is smaller than in the case of the two experiments in question. Thus in the case of 11 earlier tests in which series