the solid lines the institutional idiots.1 It is very evident in Fig. 28 that the public school defectives occupy the position at the top of FIG. 28. Intelligence Tests. Composite of Tests 6 A I, 6 A II, 6 B and 6 C. FIG. 30. FIG. 29. Memory Tests. Composite of Tests 14 and 3. Composite of Tests 13, 1, 2 and 4. The small number of cases in these curves is explained by the fact that a misunderstanding of one or two tests would throw a child's marks out entirely, as these records represent average marks and not single tests. the curve, just below the zero point, all but one case fall above - 4.5 P. E. and none fall below -7 P. E., while the other idiots rank as low as 28 P. E. Now the fact that these defectives who fall near the central tendency of ordinary ability are those who are still in the public school, although in special classes, is significant. These children have been considered to fall at the extreme of normal children, in intelligence at least. They have not been considered defective enough to be sent to institutions but have simply been given more and different attention from that given to ordinary children. Their records, as shown by the surface, overlap the records of ordinary children and those of the idiots as well. They form the connecting link between children in general and those so defective mentally as to be confined in institutions. The position occupied by these school defectives in the curves representing the memory and maturity tests is similar to that for intelligence but is not quite so well defined. In each case they fall in the upper half of the surface and in general tend to be those near the zero point. This additional proof strengthens the conclusion reached that idiots do not form a special class but belong to the ordinary distribution; and further that this distribution is a continuous one, there being no sudden break in ability, above which we find ordinary children and below which we find the idiot, but that the decrease in ability is gradual. It seems a steady progression from that of the ordinary child, through those special cases of mentally deficient children still retained in school, to those idiots found in institutions who can do most of the ordinary school work and seem to be not very different from children in general, on to those who can simply do manual labor and so down through all the gradations of complete idiocy. § 14. Results Bearing on the Generality of the Mental Defect THE third general conclusion was that there is not among idiots an equal lack of mental capacity in all lines. This fact has already been brought out in dealing with the first two questions, but a glance at Table XXXIII. (page 68) will serve to emphasize it. In th weight test there are 18 per cent. above the median for ordinary chil dren, in memory 10 per cent. and 5 per cent., and in the intelligenc tests 9 per cent. and 0 per cent. In the composites of these differen series of measurements there are 27 per cent., 24 per cent. and 1 per cent., respectively, above 2 P. E. This means that in goin from the tests of maturity to those of intelligence we find an in creasing number of idiots that fall below the standards for childre in general. Besides finding a greater number below the standard, the variability from that standard becomes greater in the intelligence tests and also the average ability as compared with the other children is lower. Figs. 24, 25 and 26 show the median for idiots in the intelligence tests to be about - 7 P. E., for memory to be 3.5 P. E. and for maturity records to be — 2.7 P. E. The idiots are nearest the central tendency for children in general in the measurements of mental traits which are chiefly tests of maturity, and farther and farther away as measurements are made which are tests of ability to deal with abstract data, They are two and a half times as far from the median for children in general in tests like the opposite test or genus-species test as they are in tests like the A test or the perception of weight. To speak of idiots then as being equally deficient in all the mental powers is false. 'Arrested mental development' must be taken to mean unequal arrests, some powers receiving a very much greater check than others. The feeble-minded child may be weak on all sides of his mental make-up (though this is not true of all of them), but that is not telling the whole story. From the point of view of the psychologist and the educator it is fully as important to know that the idiot's perceptive powers are almost two and a half times as strong and accurate as his intellectual powers and almost half as strong again as his powers of memory, as to know that he is weaker than the ordinary child in all these particulars. There is one other point to be mentioned before leaving this aspect of the subject. I believe that in the tests of motor control, of perception of form and weight and the like, the case against the idiots is not so bad as it seems to be. In each one of the measurements of this kind that were taken, not one trait but a combination of traits, one of which was intelligence, was measured. In every case there were directions given and the understanding or lack of understanding of these directions had a very large influence on the result. I believe the main difficulty with these feeble-minded is just this lack of intellectual power and not so much inefficiency in perception, motor power, etc. The block test brings this out clearly and the maze test too; the children did not get the sense of the thing, did not realize what was wanted; and the results are correspondingly poor. Much has been written of the poor muscular control possessed by the idiot, but it may very well be that he stumbles about in walking and drops things so frequently simply because he does not know just where he is to go, or just what he is to do, because he is in a chronic state of indecision or of obstructed will. In other words the real motor or perceptive power need not be nearly so bad as it seems to be, for the difficulty may be largely an intellectual one. Of cours this can only be proved by experimental evidence which will differ entiate between motor and intellectual ability; the evidence offere here does not pretend to do this. However, my opinion is that a we have found the idiot to be not far from the ordinary child as t the physical measurements of height, weight, etc., so we shall fin that in motor control and perceptive powers he is not so far away a he seems to be, but that his ability decreases enormously when th power to deal with abstract ideas is considered. The question as to whether there is any correlation between the traits observed among idiots, might be raised. But the matter of correlation is rather difficult to handle when one is dealing with such extreme cases. The usual methods do not hold. Another difficulty in answering. this question is the fact that my material is hardly However, the definite enough to warrant any decisive conclusion. results seem to show about the same lack of correlation as is found when the question is investigated with regard to ordinary people. Were there really much correlation present we should expect it to come out rather clearly, as we are dealing with such extreme cases; but there seems to be comparatively little. The correlation of memory with intelligence is shown in Fig. 31, the solid line showing the relationship of the two as it exists and the dotted line showing what it should be were the correlation perfect. Fig. 32 shows the same for maturity and intelligence tests. At the upper end of the curves in each case the correlation is very much closer than at the lower. However, as I have already stated, not much can be said on the basis of this material. § 15. Improvement among Defectives in a Year's Time ABOUT a year after these tests were made, they were repeated for some of both the defectives and the ordinary children in order to see what changes and what degree of change had taken place in each class, and how far these changes were comparable. The children who were tested a second time were the cases in the Waverley School for Feeble-Minded and the group of nine-year-old ordinary children from one of the New York City schools. Each child was marked for every test and these records compared with his record of a year ago in the same test. If the marks were the same each time the improvement was rated at zero, a higher or lower mark on the second trial being indicated by a plus or minus mark in the improvement rating. The actual marks may be found in the Appendix, § 18, in Tables XXXVII. to XLI. inclusive. Each test was then considered by itself and the percentage of the total number of cases which had improved and the median amount of improvement for each test was found, both for the deficient and the public school children. A comparison of these final marks shows the relative improvement of each class in a year's time. Table XXXV. shows these results. Comparing the amounts of improvement of the feeble-minded and the nine-year-old school children, we find that in two of the maturity tests the defectives improve more than normals, namely, in the A test, and in memory of unrelated words in which the respective ratings are 7.7 and 5.0 and +1.7 and 1.0. In the rest of the maturity tests the ordinary children improve more than the defectives. In the tests of memory, including the dictation work, the defective children improve much more than the other children, for their total record gives a change of +4.4 and that of the others only +0.3. That this change is a general one and not caused by |