Per Cent of cases showing improvementPeriod 1Period 2Period 3Based on 31 cases32·2Based on 18 cases33·366·6Based on 11 cases36·363·5100Based on all groups33·965·0100
These cases were compared with a control group chosen at random. They comprised a total of 100 children who had records for four consecutive school years.
Period 1Period 2Period 3A—Per cent of 31 cases (operated upon)32·2Per cent of 100 children at random42B—Per cent of 18 children— 20 months (operated upon)33·366·6Per cent of 100 children at random4241C—Per cent of 11 cases for 30 months (operated upon)36·363·5100Per cent of 100 children at random424141
"... Immediately after operation, there seems to be a dropping off in the quality of school work done," but thereafter a marked improvement while the random group shows a comparatively static percentage of improvement from year to year. The conclusion of the author is:
"Here seems good reason to believe that the removal of diseased tonsils and adenoids is a factor in beneficially influencing the mental life of the school child. Not only is the health impaired by failure to remove these diseased parts but the mental life and activity of the child as well."
It is conceivable that pedagogical retardation might exist without any defect of intelligence. The physical effects of adenoids and tonsils might produce a tendency to fatigue, an emotional instability and consequent lack in attention, which would seriously influence the quality of school work, even though the child were of normal or superior intelligence. The relation of physical defects to intelligence has been investigated experimentally by a method which will be employed to some extent in the present investigation. In the two studies to which I refer psychological tests, rather than school standings were used as a basis for judging the intelligence. In each the effects of treatment were measured, and in one, a control group makes possible a more accurate interpretation of results.
The first of these investigations is described by Wallin.[13]It was "an attempt to determine by controlled, objective, mental measures the influence of hygiene and operative dental treatment upon the intellectual efficiency and working capacity of a squad of twenty-seven public school children in Marion School, Cleveland, Ohio (ten boys and seventeen girls), all of whom were handicapped to a considerable degree with diseased dentures or gums, and an insanitary oral cavity." The experiment extended over one year, from May, 1910, to May, 1911. The treatment included corrective work upon the teeth and mouth, and also instruction in oral hygiene, and follow-up work by an employed nurse. Five series of psychological tests were given at stated intervals during the course of the experiment. They included tests of immediate recall, spontaneous and controlled association (opposites), adding, and attention-perception (cancellation). There were six sets of each test, numbered from one to six, of equal difficulty, and given under uniform conditions. Tests 1 and 2 were given before the treatment began, and the average was taken as the "initial efficiency." The last four, or the last two, were averaged to represent the pupils' "terminal efficiency."
The results show the following influence of dental treatment upon the working efficiency of the pupils.
1. The indices of improvement are about the same for boys and girls.
2. Improvement was about the same for older and younger pupils.
3. There were great individual differences in initial proficiency and in improvement.
4. Improvement in one test does not presuppose improvement in another.
5. There is a decided gain in every test, "and not only are the gains decidedly more frequent than the losses but the largest gains are invariably emphatically larger than the largest losses."
6. The average gains in the tests were:
Memory, 19 per cent with 8 losses and 19 gains.Spontaneous association, 42 per cent with 2 losses and 25 gains,Addition, 35 per cent with 1 loss and 26 gains.Controlled association, 29 per cent with 0 losses.Perception-attention, 69 per cent with 0 losses.Average gain for all tests, 57 per cent.
Unfortunately, Wallin was unable to form a control group, so that it is impossible to estimate accurately how much of this gain is due to the treatment of the defect, and how much to other causes, such as growth, etc. "But," the writer adds, "if we concede that one-half of the gain—and that is, I believe, a sufficiently liberal concession—is due to a number of extrinsic factors, such as familiarity, practice and increased maturity, the gain solely attributable to the heightened mentation resulting from the physical improvement of the pupils would still be very considerable. There is corroborative evidence to show that there was a general improvement in the mental functioning of these pupils. This evidence is supplied by the examination of the pedagogical record of scholarship, attendance and deportment. Most of the members of this experiment squad were laggards, and repeaters, pedagogically retarded in their school work from one to four years, but during the experiment year only one pupil failed of promotion,while six did thirty-eight weeks of work in twenty-four weeks, and one boy finished two years of work within the experimental year."
The second investigation was equally careful in its method. It was pursued by the Rockefeller Foundation, under the direction of E. K. Strong, with the purpose of examining the "Effects of Hookworm Disease on the Mental and Physical Development of Children."
The children were divided into five groups and tested at intervals of three and one-half months. The tests used were opposites, calculation, logical memory, memory span, hand-writing, form-board, and Binet-Simon. After the first test-series was given, the five groups were divided into sub-groups on the basis of this initial performance, so that the improvement was compared only for those sub-groups in which this was equal.
The improvement of Group A—uninfected children—proved to be greatest, and was taken as 100 per cent. On this basis, Group B—infected children not treated—showed the least improvement,—only 34 per cent. Group C—children completely cured of infection—improved 60 per cent. Group D—severely infected children, treated but not completely cured—improved 38 per cent, and Group Du—an older sub-group of D—improved 9 per cent as much as the normal children, and much less than the untreated younger children. Dr. Strong reaches the following conclusion:
"The figures show, then, that hookworm disease unmistakably affects mental development. Treatment alleviates this condition to some extent but it does not, immediately, at least, permit the child to gain as he would if he had not had the disease. And the figures apparently further show that prolonged infection may produce prolonged effects upon mentality,—effects from which the individual may never recover."
The following investigation was carried on during the year and a half from October, 1919, to April, 1921. The subjects were pupils at Public School 64, Manhattan, or patients at the Manhattan Eye, Ear and Throat Hospital. All were boys, between the ages of six and fourteen years. The testing in the study of improvement was done by the investigator, assisted by three other examiners, all competent and experienced in the technique of giving psychological tests.
In addition to the more lengthy experiment, a statistical study was made, comparing the intelligence levels of two groups of children, the one selected for the presence of tonsils, the other for freedom from them. These two groups were obtained from a large group of 530 children whose I.Q.'s were gained from the records of Public School 64, where, so far as possible, all children are tested upon entering school. We had, therefore, a group unselected for intelligence level.
All the children for whom we had I.Q.'s were examined by the school nurse or physician. On the basis of this examination the two groups were selected. The tonsil group consisted of those cases which in the opinion of the nurse or doctor, were pronounced enough to deserve treatment. The normal group was composed of those who were not defective, or in whom the defect was so slight as not to demand treatment. The two groups were arranged each in a surface of distribution according to the I.Q.'s of the members. The results of the distribution appear in Table I, and in Figs. I. and II.
The method employed here is based on the hypothesis that if a physical defect is the cause of retardation in mental or physical development, removal of the cause will tend to lessenthe retardation. In other words, if a child's working efficiency is lowered by the effects of adenoids and bad tonsils, their removal should, unless such lowering be permanent, be followed after a reasonable time by an improvement. But improvement in efficiency, following the removal of adenoids and tonsils proves nothing unless we shall compare it with the change in efficiency of a control group, whose members have not been operated on, and who thus still suffer from the effects of the growths.
The selection of the children for the experiment was effected in the following manner. The teachers at Public School 64 were asked to report any cases which had come to their notice, as being seriously afflicted with adenoids and diseased tonsils. In this way a fairly large group was obtained. The parents of the children were visited with the purpose of obtaining permission for examination and operation at the Post Graduate Hospital. It was fairly easy to obtain permission to have the children examined. They were taken in groups of four or five to the clinic, the experimenter attending in person every examination in order to learn from the doctors the degree of the defect. As a result of this method, we discarded all those cases where there was any doubt as to the serious nature of the defect.
From the large group examined, we were finally successful in securing operative treatment for 10 children. Discarding the cases where defect was slight, there remained a number of children who, for one reason or another, did not undergo operation. In some instances the parents refused their permission, in some they failed to keep appointments, in one or two there was sickness in the family, and in a number the hospital was overcrowded and could not receive the children. All members of this group were examined,—to the number of fifty-six, and from them the control group was finally selected.
Since we were unable to secure a large test group from Public School 64, the experiment was continued at the Manhattan Eye, Ear and Throat Hospital where opportunity was given for testing the children after they had been admitted for operation. In order to be sure that in each case the defect was sufficiently pronounced to render decisive the results of the experiment, each child's card was examined. Only thosechildren were included who were undergoing operation for both adenoids and tonsils.
It may be here remarked that mental tests were given to these children on the morning of operation, and in some cases only a short time before it. The possibility suggests itself, therefore, that the results of the tests may have been influenced by excitement or fright on the part of the patients. Actually, however, this did not seem to be the case. The children were perfectly cheerful and showed no signs of nervousness. The tests were given in a waiting room with the door closed so that any disturbing sights and sounds were eliminated. The possible lowering of the performance by the causes mentioned would tend to exaggerate the improvement shown by the retests, so that in the light of the results, it will be seen that they could have had little effect.
The test group, then, was composed of forty members; ten from Public school 64, who received operation at the Post Graduate Hospital, and the remaining thirty from various schools throughout the city, patients at the Manhattan Eye, Ear and Throat Hospital. The control group of forty was selected as previously described, and the pairs were arranged so as to have the ages of the members of one pair as nearly as possible the same.
Since the main interest of this investigation lies with intellectual development, two tests of intelligence were given: namely, Terman's revision of the Binet test, and Healy's Picture Completion Test, number II. The starred Terman was always used, since it was necessary to economize time.
It was expected that improvement in general health would probably follow the removal of the defects. This physical gain should come to light in increased height and weight. In every case, therefore, height and weight were measured.
It is conceivable that adenoids and tonsils might have no effect upon general intelligence, and yet might cause a noticeable pedagogical retardation, simply as a result of the child's physical handicap, tendency to fatigue and consequent defect in attention or sustained effort. In order to gain some measure of this physical factor, strength of grip and speed in tapping were found. An effort was made, also, to obtain teachers'estimates of the pedagogical rankings, but this was for the most part unsuccessful, since in many cases teachers misunderstood directions, and in others the tests were made too soon after the opening of school for any such estimates to be possible.
The tests described above were given before the operation to each child in the test group, allowing as short an interval as possible between test and operation. In the case of the Manhattan Hospital children, test and operation fell on the same day. In no case did the interval exceed ten days. The members of the control group were tested, each one within a week of his partner.[14]
Six months after his first test, each child was retested, whenever possible. Since some children had dropped out of the groups for one reason or another, the final number in each group was twenty-eight. It was necessary to rearrange the control cases somewhat in order to fill in spaces left vacant by those who were lost. In this rearrangement, the effort was made, 1. to pair cases whose ages were approximately the same; 2. to pair cases whose first tests were dated fairly close together. Since all the children were tested and retested under approximately the same conditions, this rearrangement will probably not greatly influence the results. The tests were always given in the same order.
The following table shows a list of the two groups, as originally paired, and as finally rearranged, with dates of tests and retests. Dates of operation are given for the first group.
Test CaseOriginal ControlFinal ControlTest IOp.Test IITest ITest IITest ITest IIJB10-15-1910-20-19lostSS10-15-194-15-20LL10-15-1910-20-194-15-20LJ10-15-19lostSS10-15-194-15-20HK10-30-1911- 6-194-30-20MG10-21-194-30-20MS11-11-1911-12-195-17-20AA11-20-195-17-20GF12-11-1912-26-196-11-20SD12- 4-196-11-20RJ12-16-1912-30-196-16-20NF12-10-195-14-20JJ12-16-1912-30-196-16-20ML12- 5-196- 9-20AG1-15-201-16-207-15-20LP1-15-207-15-20IK2-14-202-16-208-11-20AL2-14-208- 2-20HG2-10-202-11-20movedcontrol removedAC2-11-202-12-208- 2-20JF2-11-208- 3-20CL2-26-203- 1-208- 3-20JF2-26-208- 3-20MR2-26-203- 1-20movedcontrol removedSR2-26-202-27-208- 3-20PG2-26-208- 3-20IK3-17-203-17-20movedcontrol removedAO3- 8-203- 8-209-20-20SK3- 9-209-24-20RB3- 8-203- 8-20movedcontrol removedDT3- 8-203- 8-20mastoidcontrol removedAL3- 9-203- 9-20movedcontrol removedJD3- 9-203- 9-209-23-20DD3-11-209-16-20LS3- 9-203- 9-209-25-20KS3-16-209-24-20JB3-12-203-12-20movedcontrol removedHS3-13-203-13-209-21-20MR3-15-209-15-20AM3-13-203-13-209-20-20JM3-13-20lostHH4- 6-2010- 1-20SO3-18-203-18-209-22-20SS3-22-20wrong boyMA3-23-209-23-20IF3-18-203-18-209-23-20(adenoidsPK3-22-209-21-20AD3-19-203-19-209-20-20LC3-22-20(removedIB3-23-209-24-20JR3-19-203-19-20movedIB3-23-209-24-20JN3-20-203-20-20movedMA3-13-209-23-20LF3-20-2010- 1-20HS3-20-203-20-209-21-20SB3-25-209-21-20II3-26-203-26-209-24-20BF4- 5-2010- 1-20UF3-27-203-27-209-29-20LF4- 7-2010- 1-20SM3-27-203-27-209-30-20LG4- 6-2010- 1-20AM3-29-203-29-209-29-20BG4- 6-2010- 1-20CK3-29-203-29-209-29-20NF4- 7-2010- 1-20FB3-30-203-30-209-29-20JF3-26-2010- 1-20AA3-30-203-30-209-23-20LS3-31-203-31-20movedcontrolremovedMA4- 5-209-30-20FT3-31-203-31-209-28-20LP4- 1-204- 1-20movedHH4- 6-2010- 1-20
The statistical study compared two groups of cases in respect to I.Q. These groups were selected from one large group, on the basis of presence or absence of tonsillar defect. The tonsil group was composed of 236 cases, and the normal group, of 294. The distribution of the two groups according to intelligence is set forth in Table I, and in Figs. I and II.
Tonsil GroupNormal GroupI.Q.No. of CasesPer cent of CasesNo. of CasesPer cent of Cases40- 502·80050- 601·42·760- 7072·941·470- 80218·9299·880- 904519·05217·790-1008033·910736·4100-1105523·36722·8110-120177·2248·1120-13062·593·0130-1402·800140-1501·400Average94·995·4Median95·395·6Q8·7058·27σ14·412·2
From these it is evident that the two groups are practically equal in intelligence. The average I.Q. for the normal group is 95·4, as compared with 94·9 for the tonsil group. The medians are equally close,—95·6 in the normal group and 95·3 with the tonsil cases. The difference in variability is negligible, Q being 8·705 and σ 14·4 in the tonsil group, while in the normal Q is 8·27 and σ 12·2. The two cases with the lowest I.Q.'s were tonsil cases, but the three highest I.Q.'s also belong in this group.
Fig. 1. Distribution of I.Q.'s. Number of cases.
Fig. 2. Distribution of I.Q.'s by percentage of total number of cases in the group.
If the frequencies are expressed in terms of per cent of the total number of cases in the group, the two may be compared further. The following details are noticeable.
I.Q.Per cent of Tonsil GroupPer Cent of Normal GroupBelow 704·12·1Below 9032·029·6Above 11010·911·1Above 1203·73·0Above 1301·20
In other words, in the percentage of cases below normal intelligence, the tonsil group exceeds by 2·4 per cent. The percentage of defective cases is also slightly greater in the tonsil group—the difference here being 2 per cent. The normal group has a negligible predominance of bright cases,—only two-tenths of one per cent difference, while with the very superior cases, the tonsil group again exceeds,—by 1·2 per cent. The per cent of the tonsil group which reaches or exceeds the median of the normal is 49 per cent.
These figures seem to indicate remarkable similarity between the two groups considered. The two distributions are almost identical. While the slight predominance of cases below normal mentality in the tonsil group may indicate a very feeble tendency toward coincidence of tonsillar defect and mental dullness, it does not seem large enough to be at all significant. This is especially true when we consider that the tonsil group exceeds in superior children. If we allow the preceding contention of coincidence between dullness and tonsils, must we not argue here in the same manner for a tendency toward coincidence of superiority and tonsils?
The chief source of error in this part of the study is the fact that the throat examinations were not conducted by the same person throughout the investigation. For this reason there must have been some slight disagreement as to what should constitute a reportable case. In the event, then, of a positive relationship between tonsil defect and lowering of the intelligence quotient, placement of normal tonsils in the "tonsil" group, and of diseased tonsils in the "normal" group would raise the first, and lower the second, thus tending to conceal the difference between the two. On the other hand, the cases where disagreement would occur would naturally be those of slighter defect, in which the intellectual retardation would be less likely to occur, so that the result wouldprobably be merely an increased height at the overlapping portion of the curves, with no change at the ends.
In any case, the two examiners had worked together previously, so that each must have been somewhat familiar with the opinions of the other. They were aware, also, that pronounced tonsillar defect was what we were attempting to detect. However this may be, there must always be some disagreement in diagnosis. When this is allowed for, the results of the investigation may be taken for what they are worth. Contrary to expectation, there seems to be very little difference in intelligence between a group of children whose throats are normal, and one in whom the tonsils are diseased or badly enlarged.
The complete results of the tests and retests are collected in Table II, where each control case is listed immediately below its respective test case, and where age, height, weight, grip, tapping rate, I.Q., and score in Healy Picture Completion are shown. From these data the more detailed observations have been made. The improvement of each child in the various tests has been computed, and a comparison drawn between the two groups. As we have previously stated, any improvement shown by the test group in excess of that of the control group, may be looked upon as significant.
Let us consider first the improvement of the children in general health, as shown by height and weight. In Tables III and IV we have tabulated the results, in such shape as to permit of comparison. An inspection of these tables will establish the fact that after a six months' interval, the test group shows, in respect to height and weight, a very slight gain over the control group. In weight, the average of the amounts by which the test group gains exceed the control group gains is 1·37 lbs., and in height, only ·16 inches. The medians of these amounts are 1·2 lbs. and ·2 inches respectively. Comparing the improvements for the two groups, we find that in the case of the weights, the smallest gain (a loss of 1·2 lbs.) occurs in the control group, while the largest gain (10·7 lbs.) is in the test group.
Blank spaces indicate where tests were omitted for one reason or another
NAgeWeightlbs.Heightin.Grip, Kg.best hand1212121217- 78- 150·454·24647·613121C8- 18- 753·557·246·447·8111326- 97- 340·942·942·641·1992C7- 17- 752·357·445·247101238-8- 65559·54748·412·814·53C9- 910- 361·562·951·752·9141548-109- 451·154·247·549·294C9-1010- 449·45148·9529·556- 16- 7454744·945·2115C8- 28- 856·25746·648·11265- 25- 843·844·543·143·986C7- 17- 750·652·545·447·310·576- 77- 139·94142·944·876·57C6- 77- 138·438·741·943·291088- 69-60·863·350·851·8108C8- 58-1145·452·146·847·6151699- 49-1050·653·248·149·410·5139C9- 610-59·861·451·955·216·521106- 77-148·951·446·147·712·51110C7-7-647·147·545·647·21015116- 77-47·847·545·847·7111511C6- 87-141·642·543·644·911·511·5127- 88-24852·544·81412C7- 1-84144·541·543·364·51313- 313-10909861·56526·528·513C14- 615-74·776·856·857·822231411- 912-456625151·6161514C11-1012-481·98657·958·322241510- 310-1057·551·115·515C10- 110-767·270·350·1511515·51610- 911-3565751·652·31917·516C10- 911-351·25048·749·51010178- 18-75748·71417C7-108-445·344·8108·5187- 27-858·247·31118C6-117-545·34746·747·186·51911- 411-109096·357·759222119C7-118-552·454·446·747·21512207- 17- 744·247·21120C7- 37-1061·36649·6551512·52111-11- 670·776·554·116·516·521C10- 110- 762·46749·650·419152210- 911- 373·35356·41822·522C11- 712- 170·780·556·858·119·521·5238- 79- 151·747·811·515·523C8-119- 464·166·551·453·114·514249- 810- 258·562·551192024C10- 210- 8606150·151·515152510- 110- 755·559·55050·81425C10-1011- 463·363·850·250·912·521·5269- 810- 263·874·551·654·31426C10- 410- 964·26751·452·32016·5276- 77- 143·745·49627C6- 36- 9414444·645·4892812-1113- 571·375·554·955·823·52128C13- 814- 274·279·853·454·521
Blank spaces indicate where tests were omitted for one reason or another