perform, and then throw out all that are not fairly representative. average error will be higher than in normal psychology, but the nature of the material necessitates it.

The sense being the basis of mental life, the first investigations were made concerning them.

TOUCH.-Observers are agreed that touch is imperfect or obtuse among the feeble-minded.† However, it is a subject very difficult to get at, especially among the lower grades on account of their mental dullness and lack of attention. Lombroso finds a dullness of touch among the criminal and insane. In order to investigate the sensibility of touch among the higher grades of feeble-minded children, the author made use of Scripture's Touch Weights, the common compass ethesiometer not being applicable. There were twenty of these weights ranging from one to twenty milligrams. The back of the hand was the point selected for testing. The method of work was to begin with the smallest weight and find one whose weight was just perceptible. There were thirty-two boys and thirty-seven girls tested. The results were :

This shows touch to be con

The normal according to Scripture is 2.0. siderably dulled among the feeble-minded, especially among the boys. The high mean variation is very noticeable, and is characteristic of the feebleminded. Dividing the girls and boys into three groups according to their mental ability, as estimated by their teacher, A being the highest, we have:

This further indicates that the fineness of touch depends on mental ability. This is more evident when we consider the fact that there were a . number whose touch threshold did not lie within the range of weights. Of these there were four boys graded C, and eight girls graded, one A, one B, and six C. Three boys graded C and one graded B were unable to perform the test, also four girls graded C and one graded B.

Among those tested there were six Mongols. These all showed a remarkable dullness. Four of them did not come within the range of the weights, and the other two gave readings of eighteen and twenty.

PAIN. That a large number of the lower grades of feeble-minded children lack in some degree the sense of pain, is a fact of frequent observIreland: Mental Affections of Children, p. 303. Sollier: Psych. de l' Idiot et de l' Imbecile, p. 54. L Homme Criminel, Vol. I, p. 315.

ation. They beat themselves, pound their heads against the walls and floors, pick holes in themselves, bite themselves even to making great ulcers, and pull out their hair with no seeming discomfort. One girl when angry will scald herself severely. However, the total loss of pain is not thought to be so common as among the insane.||

For the purpose of investigating the pain sense of the feeble-minded, the author made use of Cattel's Algometer. This consists of a spring dynamometer, by means of which given pressure can be exerted on any surface. "Attached to the lower end of the spring is a cylindrical piece of brass. This is capped with hard rubber, which is applied to the surface to be stimulated. The cap which comes in contact with the skin is hemispherical and about eight millimeters in diameter. The pressure is exerted by the hand of the experimenter, and the amount of pressure is indicated in killograms." The stimulus was applied to the volar surface of each hand over the fifth metacarpal, and to the forehead about two centimeters above the nasal. The pressure was increased at the rate of two kilograms per second. Each child was given five trials, seven days apart, during the summer of 1899. Taking the children's reaction time at 0.338 sec.,* and the normal time at 0.150 sec., the results were reduced one killogram. The mean variation was calculated for each person and then averaged. The results were as follows:

Comparing our results with those of Griffing, we find that our children. are more sensitive in their hands than normal people. The forehead probably gives more exact results, as the structural conditions are more constant, here the boys are much less sensitive, the girls being about normal. The results of McDonald, although obtained with the same instrument, are

in some respects higher, showing, as he contends, that sensitiveness to pain depends on sociological condition. Granting this the pain sense of our children would not be obtuse. Our results show the girls to be more sensitive than the boys, and that both are more sensitive in their left hands, in these respects agreeing with normal people.§

Grouping the children into groups according to mental ability, A being brightest, we have:

The brighter boys have a greater sensitiveness for pain than the duller boys. With the girls such is not the indication except, perhaps, on the forehead. Thickness of hands lessened the Sensibility for pain, thinness of hands increased it.

Pain on the forehead continued after the stimulus ceased with twentytwo boys in 33.5 per cent of trials, and twenty-seven girls in 37-7 per cent of trials. With the greater number of the children this occurred only one or two times.

Five boys, or 12 per cent of those examined, gave from one to five tests above the reading of the instrument (13 kg.). With one boy this was always the case. The readings taken showed the boys less sensitive than the average. Two girls, or five per cent of those examined, gave readings above the range of the instrument.

The ages of the children ranged from fourteen to twenty-five years. The sensibility to pain was not observed to depend on their age.

Griffing concludes that variations in sensitiveness to pain is due to "constitutional nervous difference," and to thickness of the skin, propositions to which we agree. Gilbert† finds that sensitiveness decreases with age up to nineteen years among normal children, and that their mean variation is high. Carmant finds that dull children are less sensitive to pain than bright ones, and those dull in mathematics are more sensitive on the right side. With this last statement our results do not agree.

MUSCLE SENSE.-Among the lower grades of feeble-minded children, we find those among whom the muscle sense seems to be absent, they lie or sit still all day, and never move unless forced to by some outward circumstances. Among those of higher grade, it is lacking, as shown by difficulty in walking and moving themselves. This deficiency can exist without marked deficiency in the other senses. Children have been known who could not dress themselves, but could learn to read and write.

University of Iowa Studies in Psych., Vol. 1, p. 11.

*Op. Cit., p. 15. † Op. Cit., p. 11.

Amer. Jour. of Psych., April, 1899, p. 138.

See Voisin: Sur L'Idiotie, p. 138.

With others this sense may be excessively developed, as shown by a continual movement and a desire never to be at rest. Here we meet with the tics and various automatic movements of feeble-minded children.§ Fully fifty per cent of low grade children have some such movements.

In order to test the muscle sense of our school children, the writer made use of a series of weights, all of the same size, ranging from one hundred to one hundred and thirty grams in steps of three grams. The child was required to lift each weight by thumb and fore-finger, in this way comparing the one weighing one hundred grams with each of the other, and then to state which one seemed the heavier. Each test was repeated in an inverse order.

Twenty-three boys and twenty-nine girls were tested. Among the boys, three were unable to do the test, and four, or twenty per cent, could detect no difference in the series. Two per cent would be a fair estimate for normal children.

The only figures we have for normal children are those given by Gilbert for lowa school children. However, he used weights ranging from eighty-two to one hundred grams. Comparing our results with his, we find that our boys have an average of 2.7 grams higher. Grouping our boys according to mental ability, we have the following averages as the least perceptible difference in grams.

This shows a finer perception with least variation on the part of the brighter boys.

Of the twenty-nine girls examined, seventeen, or 58.6 per cent could perceive no difference within the limit of the series. The twelve remaining girls gave an average only 0.5 higher than Gilbert's figures for normal girls. Grouping them according to mental ability we have:

This also shows a finer perception on the part of the brighter girls. Those who could see no difference within the limit of the series, were thus grouped, A two, B eight, C seven.

Thus we find a dullness of the muscle sense among the feeble-minded, varying inversely as the mental ability.

HEARING.-Observers have not had much to tell us of the hearing of the feeble-minded. Deafness, however, is thought to be less prevalent than among normal children.

Our tests consisted in finding the highest and lowest tone which could be perceived and the least perceptible difference of tone. Sixteen boys and twenty-one girls of larger singing class were examined. For finding the highest perceptible tone, Galton's Whistle was used. For the boys this

consisted of 53,000 vibrations, with a maximum of 104,000 and a minimum of 29,600. For the girls the average was 63,000, with a maximum of 125,500, and a minimum of 25,500. The average for normal people is usually given at 50,000. For finding the lowest tone Appun's Reed was used. For the boys this was found to be a tone of 18 vibrations, with a maximum of 22 and a minimum of 14; and for the girls it was 18 with a maximum of 30 and a minimum of 13. A tone of 16 vibrations is usually given as the lowest perceptible to the ears of normal people. In order to find the least perceptible difference of tone a tone tester was used. This consists of a reed whose length can be adjusted so as to give the various tones of an octave. The tone A, 435 vibrations, being given, we then proceeded to find what difference of tone above and below this the child could distinguish. For the boys this was tone, with a mean variation of; for the girls it was with a mean variation of.

Our experiments show nothing abnormal in respect to hearing, however, they were performed on our brightest children.

VISION. The visual apparatus of idiots is generally good. However, seven or eight per cent have been found blind from their first year. Stra bismus is frequently found, and nystagmus and squinting are common. Abnormalities of the iris and pigmentary retinitis are also found. Schleich finds hypermetropia very common among idiots and imbeciles.†

The common means of testing vision by means of a Snellen test chart is only of limited use among the feeble-minded, being of course limited to those who can read. However, twenty-five boys and nineteen girls were tested with it. Of these only three boys or seven per cent of all had normal vision in both eyes. Nine per cent of the children had vision of §, and the remaining eighty-four per cent had vision ranging from 1 to 3. Dr. West found forty-one per cent of the children in the schools of Worcester, Mass., with defective vision. Eighty-four per cent of the children were astigmatic.

This test being controlled by errors of refraction and being of limited use, we sought another. To this end we made use of a color wheel, on which was mounted a piece of red paper in the usual manner, so that any amount of white could be mixed with it. The various shades thus produced were compared with a piece of the original red paper. Beginning with no white on the wheel, white was gradually introduced until a difference was noted, then gradually reduced until no difference was indicated. The mean of these readings was taken and the variation noted.

For thirty boys the average was thirty-two degrees, with a mean variation of nine degrees; for twenty-three girls the average was twenty-three degrees with a mean variation of seven degrees. According to the investigations made to establish the validity of Fechner's law, the normal would be 3.6 degrees. Consequently we have a visual dullness on the part of the feeble-minded, it being six to eight times that of normal people.

*Ireland: Op. Cit. Volsin: Op. Cit., p. 125.