Page:Mind (Old Series) Volume 12.djvu/91

 78 J. JACOBS : EXPERIMENTS ON Table, giving the averages for the first and second halves of the various classes at the North London Collegiate School for Girls :, Numerals. Letters. Form. 1st half. 2nd half. 1st half. 2nd half. VI 10-5 9'1 9 8-1 Up. V 9-8 9-1 8-8 8-2 V 7-9 8-6 8-1 7-8 L.V.K 8-2 8-1 8 8-1 LowV 8-5 9 8-2 8 Up. IV. K 8-4 8 8-4 7'5 Up. IV 8-4 7-8 7-4 6'5 IV. R 8-6 7-6 7-2 6'9 IV 8 6-6 7 6-5 L. IV. E 8 6-7 7-1 7-5 L. IV 7-5 7-5 7 6-3 Up. Ill 7-4 6'4 6-4 5-4 III 7-8 8-5 6-7 6-4 II 6-8 4-9 6-5 6 1 7-4 7-1 6-8 7 Here the general superiority of the averages for the first half of the class comes out distinctly, though with exceptions which in many cases allow of special explanation. The only difficulty is the very small extent of variability : in order to get a wider range, and also to test the obvious deduction to be made from these figures, it was suggested by Mr. Francis Galton that experiments should be tried on idiots, and he kindly undertook the inquiry in conjunction with Prof, Bain and Mr. Sully. The detailed results are given below. At Earls wood the average span was as low as 4, and much the same at Darenth. ' Idiots ' differ so much as to make it, indeed, hardly possible to speak of average results ; but it appears that few, if any, attain to the normal span, and that a good number of those who can ' speak ' at all are unable to repro- duce more than 2 numerals. This notable concomitance of high span and high place in form, though at first sight surprising, is perhaps nothing more than a corollary of the one previously shown. If the span rises with age, and is thus seemingly a measure of a pupil's relation to the standard of his or her age, it should not be surprising that a pupil with a span higher than the normal should take rank above those of the same age. At any rate, whatever be the cause, the above facts are too consistent and widespread to leave much doubt as to there being a definite connexion between high span and high place in form. And, so far as high place in form can be said to measure ability, the span may serve as some indication of ability. This at once raises the question as to what is the exact power of the mind which is involved in reproducing these sounds. In our experiments we have simply tested the power of temporarily retaining sounds long enough to reproduce them correctly. We