"As a rule the error and uncertainty of memory decrease wi
intelligence, the results showing some variations probably due to t
number examined.”

The chief question with regard to all this work is whether t
tests were within the comprehension of the children, whether the
really understood the directions. In both the experiments in tas
and reaction time it is extremely difficult to make subjects unde
stand just what is wanted, and with the feeble-minded this wou
be doubly true. In some cases the method used is indicated
roughly that one does not know how much the results mean.

Johnson reports in Vol. III. of the Pedagogical Seminary thr
sets of tests on 72 feeble-minded children-a test of memory sp
for digits, of motor control and of the time of uncontrolled associ
tion of ideas. For the memory test the results are roughly as follow
"Approximately 25 per cent. of idiots reach or exceed the abili
reached or exceeded by 50 per cent. of ordinary children. This d
ference is not much greater than between boys and girls in spelli
ability." As Johnson points out, the lack of retentiveness, phys
logically speaking, is not a prominent factor in feeble-mindedne
The apparent lack may be due to lack of attention or will power.

In the experiment on motor control, 12 feeble-minded childr
were tested with the ataxiagraph. They seem in general to
slightly below the average ability in motor control attained by n
mal children.

The greatest difference was found in the third test, the time
uncontrolled associations. Thirty children were tested, the wor
used being-house, tree, chair, ship, clock and Fourth of July.

Compared with results obtained by Cattell and Bryant from normal children, the idiots tend to make simple objective (rather than logical) associations. This, then, is the gist of the evidence on the subject and of course the main criticism upon it is that the tests are too narrow to admit of a conclusion as to the mental ability of idiots. The digit test has been felt by many experimenters to be unreliable as a real measure of memory, for in the first place it measures only a very special kind of memory, and that dependent upon mere physical retentiveness, and in the second place the results gained from successive tests upon the same individual have such a wide variability as to render them of little practical value. From the standpoint of method another objection is the fact that these results are comparable with the records of children in general only with difficulty. So although this evidence may suggest the presence of eertain differences between ordinary children and defectives in certain abilities, it does not go deep enough nor cover a broad enough field to warrant definite conclusions. I have endeavored, therefore, to add to the work in this field by giving exact measurements of a number of traits, both physical and mental, in defectives, and in such a way that a comparison with the general run of people is possible. The results of such tests will, I think, throw some additional light upon the psychology of mental defectives, but I will postpone any further general statements until I have given the facts themselves.

§ 5. Statement and Discussion of the Particular Problems of this Research

I HAVE Sought to determine (1) whether the mental defects of idiots are equaled by the bodily, (2) whether idiots form a separate species or not, and (3) whether the entire mental growth is retarded, that is, whether there is a lack of mental capacity all around.

The decision of the best thinkers in this field as to the first and the third questions is pretty clearly shown by the definitions of idioey quoted earlier in this report. Physical defects are so closely associated with mental deficiency, in the minds of some writers, that we find such defects mentioned as signs of idiocy. "It is frequently indicated by outward physical abnormalities or an imperfect general conformation of the body with usually shortness of stature." the majority of cases there will be found to exist some physical abnormality or blight or peculiarity that will give you a clue to the retarded development of brain and mind." "The evidences of constitutional weakness, of slow growth, inferior size, of defects in the formation of palate, teeth, ears, skull, etc., are associated with poor sight and hearing... and psychic weakness in all or any respects."

"The idiot, commonly dwarfed and undersized, exhibits tho signs of physical weakness which at once betray mental degener tion."

"There is a stunting of the whole physical development; th stature is undersized or even dwarfish . . . the special senses, esp cially hearing, are blunted. In eighty per cent. of cases the so-calle stigmata of degeneration are present (Wildermuth), viz., malform tion of the eyes, mouth, nose and especially the lines of the face. G. Tarbell says that idiots are about two inches shorter and ni pounds lighter on the average than ordinary children of the san age. Dr. Shuttleworth agrees with him in his general conclusi that in physical development they are below what is considered normal, but does not endorse his actual figures. On the whole, the the tendency is to consider mental defectives as ill grown, poor developed individuals.

In the answer to the second question noted, by far the weight opinion is on the affirmative side and the majority of writers see to take it for granted and to consider the contrary opinion not wor discussion. The two points of view are represented by the followi quotations:

"As the scale of imbeciles ascends, it is found that the conditi is evidenced not so much by low obtuseness as by irregularity intellectual developments. This seems to make the difference 1 tween the extreme stupidity of the lowest of the healthy and t highest form of the morbidly depraved type. . . . The two co ditions do not merge gradually into each other."-Dr. J. B. Tul "We have then in the ascending scale, from imbecility upwards, t irregularity of mental conformation, and then again separated as a clear line the uniformity of dullness of a low class of the healt type.... Belonging, so to speak, to a separate series is the low of the healthy-the dullard."-Report on Physical and Mental Aff tions of Children-London.

Sollier would go still further, for he classifies idiots and consid these divisions as representing entirely distinct and independ classes. He believes that idiocy is a symptom, imbecility a dise and that they are 'entirely distinct and different.'

"The high-grade imbecile, who is almost normal, while clos approximating the backward or feebly-gifted child, yet differs that he suffers from absolute defect, which may in a measure supplemented by strengthening those things that remain to him, which can never be wholly supplied or restored. His defect is. only limited mental capacity, but the psychic forces are wanti feeble or backward in quality. . . . The feebly-gifted or backw

child has not crossed the border line and by making haste slowly and avoiding risk of over-stimulation may finally reach the goal open to all normal minds, though by a more circuitous route. He is not a mental defective, but a mental invalid, so to speak."-Barr.

The opposite opinion is held by the following writers:

Seguin says that more than 30 per cent. of idiots and imbeciles put under suitable instruction have been taught to conform to social and moral law and rendered capable of order, of good feeling and of working like one third of an average man. More than 40 per cent. have become capable of ordinary transactions of life under friendly control; of understanding moral and social abstractions; and of working like two thirds of a man. And lastly, from 25 to 30 per cent. come nearer and nearer the standard of manhood, till some of them will defy the scrutiny of good judges when compared with ordinary young men and women.

Ireland writes: "Imbecile children have a complete though weak outline of all the human faculties. In their minds every species of mental operation is performed, though on a small and feeble scale. They may have poor judgment, a weak memory, a feeble power of comparison, a beggarly imagination, a fitful attention, but they do possess judgment, memory, comparison, imagination and attention in varying though in meager proportions, and all these can be educated and increased by exercise."

Galton says: "Analogy clearly shows there must be a fairly constant average mental capacity in the inhabitants of the British Isles, and that deviations from that average-upwards towards genius and downwards towards stupidity-must follow the law that governs deviations from all true averages.

According to his estimates there are 250 eminent men to every million and 280 idiots to every million of population in Great Britain, and so he concludes, "Eminently gifted men are raised as much above mediocrity as idiots are depressed below it."

Thorndike writes: "The ordinary usage of language tempts us to think that children can be divided sharply into normal and abnormal, or into hearing and deaf, or into healthy and hysterical; but ordinary observation should teach us that within the human species sharp lines of distinction rarely correspond to reality. Thus we know that children do not form these separate groups, the bright, the ordinary and the dull, but there are a very few bright, others less so, others still less so, others still less, until we reach the lowest idiots by a gradual passage along the scale of intellect." Here we have the two points of view, one which says that the idiot is one apart by himself, belonging to a special species; and the other which

holds that the mental defective simply falls at the extreme of the low end of normal frequency of distribution, that the idiot occupie something of the same position as the genius does, only at the othe end of the scale of human intelligence.

As to the third question, the idiot has certainly been considere as an individual in whom mental capacity in all directions is lack ing. The phrases, 'arrested mental development,' 'mental enfeebl ment,' 'arrested development of the intellectual faculties,' are sca tered rather indiscriminately through the books dealing with th subject. General mental deficiency seems to be the acknowledge characteristic of the intellectual nature of the idiot. "Typically t feeble-minded child is weak on all sides-weak in perception, atte tion, memory, in power over number and language, in combinatio in judgment, in mental endurance, and no less defective in touch, hand power, in general bodily activity and constitutional vigor

"This form of defective mental development is characterized a moderate degree of mental incapacity, which is however of eq prominence on all sides of the mental life; it may, however, invo chiefly the moral field, when it is sometimes called moral imbecil

Idiocy is characterized by a more profound degree of mer incapacity than imbecility."-Defendorf.

"A child, the feeble-minded must ever be by comparison and competition with normal people, but even a child may be brough fill acceptably a life of service in his simple sphere, however limi and in that, by constant exercise, feeble power may be raised to maximum point and kept there possibly for some years."-Barr

"In idiots the weakness is general and involves the whole mi The work which has lately been done on the correlation of me abilities in normal individuals might tend to make us feel a sceptical as to this point of view. However, as has been alr stated, practically nothing has been done that can be pointed to basis for the affirmation or negation of such statements as those quoted.

It was then to find some reliable answers to these three ques about which opinions differ so materially, that this investigation undertaken.

§ 6. Description of the Tests

MEASUREMENTS were taken of the following mental and ph

traits:

Mental Traits. Efficiency of perception (1 and 2); mem unrelated ideas (4); memory of related ideas (3 and 14); abil the formation of abstract ideas (5); ability to appreciate re