The Relation of Mental to Physical Growth
The Psychological Clinic Copyright, 1923, by Lightner Witmer, Editor. Vol. XV, No. 5 January, 1924 :Author: William Filler Lutz, A.M. y University of Pennsylvania.
This paper is the result of an investigation ot the relation between physical and mental growth on more than a hundred boys who were given an intelligence examination (Binet, Cylinders, Auditory and Visual Memory Span), combined with a very complete physical examination, including blood pressure and pulse readings, and, on the suggestion of the physician under whom I was woiking, an estimation of physiological age. The full examination took about an hour and a half, but often, to avoid fatigue, the physical examination was given on one day and the mental on another. On reviewing the data obtained, I think the time was well spent in this small but intensive study, as the results are in agreement with previous investigations in this line, and also because they are, I think, the first in which an intelligence examination by an approed scale and a physical examination of such detail have been made on so many boys of these ages.
Dr J. H. IvIcCurdy1 at Clark University did some work in correlating physical and mental growth, but as his “Intelligence rating was more a scholarship rating based on school grades and by different teachers with different standards, it does not give a definite or standard grade for the estimation of intelligence. In his work, the items studied were heart rate, blood pressure, pubescence, height, weight, strength, lung capacity, and scholarship. 1 have used the same items with the exception of strength tests. In the matter of height-weight, this study is in agreement with that of other observers?that a high percentage of those superior in height-weight indices are also superior in intelligence; that weight alone is a less positive factor, for the over-weight boy is not usually over-weight mental^; that in chest capacity there is the same agreement, in that nearly all the boys of superior intelligence had a chest capacity above the average.
1 McCurdy, J. H. “Physical Efficiency Tests During Adolcsccncc.” Reprinted from the Transactions of the loth International Congress on Hygiene and Demography. The investigation of systolic blood pressure and intelligence is not so clear; so many factors must be taken into consideration? nervousness, fatigue, physical condition and also the fact that blood pressure in boys is greatly influenced by physiological age, the normal pressure in the various stages of pubescence having a considerable range?in P 1 (beginning of pubescence) from 94 to 108; in P 2 (mid-pubescence) from 100 to 128; in P 3 (post-pubescence) from 96 to 118, although there is considerable variation even here; there was evident a gradual but not an abrupt rise of blood pressure in pubescence. As a general rule, the duller boys ran a lower systolic blood pressure at the corresponding physiological age than the boys of the superior intelligence group, which agrees with the small amount of previous work in this field. McCurdy says:1 “It may be noted, however, in a few cases, that a high rate, a large variation in heart rate in changing from the horizontal to the standing position, and also a low blood pressure, went with poor scholarship.” Very little work has been done in this line, but it seems a very reasonable hypothesis to assume that the activity of the central nervous system operating on its highest level (Hughlings-Jackson’s threelevel theory2 of intellectual activity is not uninfluenced by the force and rate of the blood supply. “The higher centers are built upon the lower ones; intelligence and morality are related to the physical integrity of the lower centers.”3
As the result of the observation of blood pressure in 2300 cases, Dr Judson and Dr Nicholson4 state that “Systolic blood pressure varies from 91 mm. in the 4th year to 105.5 in the 14th year; the widest variations are from 10th to 14th year, with a rapid elevation in 14th year during adolescence,” and, “Blood pressure readings will furnish a means of determining physical tone of a large number of children who are below par but have no demonstrable pathological lesion.”
It may also give an index of mental tone, especially in alertness and dullness as related to normal, bright and dull types. Dr Faught5 makes this observation which is probably of diagnostic value both in mental and physical fields?”Essential Hypotension: occasionally there are cases which seem to have a constitutionally low blood pressure. These cases show no definite signs of disease and no discoverable cause can be assigned for this 1 McCurdy, J. H. “Adolescent Changes in Heart Rate and Blood Pressure,” p. 10. (Thesis Presented at Clark University, Worcester, Mass., June, 1909, in partial fulfillment of the requirements for Master’s Degree.) 2 The Three Level Theory. Journal of Mental Science, 1887-1888, XXXIII, pp. 25-28. ! McCurdy, J. H. Op. cit., p. 3.
Judson and Nicholson. American Journal Diseases of Children, VIII, 1914, p. 267.
5 F. A. Faught, M.D. “Blood Pressure from the Clinical Standpoint.” 1914. condition, though sometimes it may develop later that this state was in reality an early sign of tuberculous infection. Such individuals are frequently unequal to any particular ejjort either mental or physical. This is in agreement with the suggestion advanced in this paper that the “dull” group has usually a blood pressure below the average for their age.
The investigation of physiological age seemed to yield more definite results. That there is a direct relation between physiological age and mental growth has been suggested by several investigators, but very little work has been done and few positive statements are to be found. Baldwin1 says, ” Physiological age is, the writer believes, directly correlated with stages of mental maturation,” and, ‘’another experimental study just completed shows that the mental age of the individual bears a direct relationship to the physiological age as indicated by height and weight. The results show that at each chronological age the physiologically accelerated bos and giils have a higher mental age than those of the average 01 below the average physiological age.”
Dr C. Ward Crampton2 says, “Earlier pubescence favors good scholarship; later pubescence, poorer scholarship. Irving King says ” over-age individuals in all the three physiological stages aie inferior to those of normal growth.” The results of this investigagation show, to remarkable degree, that almost all the earlier pubescent group were of superior intelligence type with Intelligence Quotients ranging from 110 to 169; that those who may be called “Dull”?I. Q. under 90?had a retarded pubescence; in the normal ?90-109 Intelligence Group?the pubescence was as a rule normal In the normal group, pubescence begins at 13.5 years, and post-pubescence at 15.5-16. (Godin4 states that the average time from P-l to P-3 is about 18 months.) In the dull group, pubescence starts at 14.5, but none of this group have reached postpubescence at 15 years, and some not at 17 years. In the Superior Group, pubescence had begun in the majority of cases at 12.5, and had been, or would have been completed at 13-13.5?apparently 4 to 6 months less time is taken in maturing in this group than in the others. So that in this group ot 100 average boys, taken as they come, from different social groups but all oi American parentage and medically in good health, post-pubescence 1 Baldwin, Bird T. ” The Physical Growth of Children from Birth to Maturity.” University of Iowa Studies in Child Welfare. Vol. I, No. 1. June, 1921.
2 Crampton, C. W. “The Influence of Physiological Age Upon Scholarship.” The Psychological Clinic, Vol. I, 1907, pp. 115-120. 8 King, Irving. “Physiological Age and School Standing.” The Psychological Clinic, Vol. VII, 1914, PP. 222-229.
4 Godin, P. Recherches anthroporactriquep sur la Croissance, Paris, 1902, pp. 180-197. is reached as follows: in the average (normal) intelligence group at 15; in the inferior group at 16, and in the mentally superior group at 12.9 to 13 years.
This is in agreement with the views advanced by Crampton and Baldwin, who have done the most, and almost the onfy work in this line, that early pubescence favors good scholarship, and later pubescence, poorer scholarship, and that the over-age individuals in all three stages of Physiological Growth are inferior to those of normal growth; that superiority in height-weTght and lung capacity are directly favorable to mental growth and school efficiency, so that a sound mind is most likely to be found in a sound body. Binet says that native intelligence appears to improve but little after the age of 15 or 10?” although the location of this point is not exactl}’- known.” May not this point be the establishment of physiological maturity? At this time the whole endocrine system is functioning. May not the full establishment of this system be necessary for the attaining of the maximum level of individual intelligence? Basic intelligence then is established with the attainment of adult endocrine function, the chronological time of which varies with the individual, and cannot be fixed at a definite chronological age. Therefore, in adolescence, before a definite diagnosis of mental retardation be made, the physiological age of the individual should be established; for it is possible for a child to be of normal mental growth for his phj^siological age, and yet fall short of the mental age required by the tests for his age in years. In such cases of late physiological growth, a final statement of mental age must await physiological maturity. Dr Crampton1 says, “We cannot tell from the number of years which the individual has lived what stage of development he may be in. The pedagogical and chronological age based upon it do not give us trustworthy information. The change from an asexual to a sexual life may occur at any age from 0 to 20, and when it does occur the changes are profound. In the short space of six months the child becomes a man or woman. New mental abilities appear while others disappear. At this time the most important epoch in life, second only in significance to birth, the child commences a period which can only be likened to an explosion of growth and development. After a variable length of time, a year or year and a half, a slowing down process arises and the mind and body proceed with a period of ripening that we call adolescence.”
If these facts be definitely established by farther investigulions i”The Significance of Physiological Age in Education.” Transactions of the 15th International Congress on Hygiene and Demography. 1912, p. 225.
which are on the way, it would clearly indicate that those factors which tend to bring about early maturity should be more clearly established with their relations to physical and mental vigor. In the educational field, it would indicate, as Baldwin1 well says, “that tall healthy children of accelerated physiological age be encouraged to proceed as rapidly as possible within the limits of thoroughness and endurance through school, and that the small, short, underheight children of retarded physiological development be detained longer in the normal and lower grades, doing supplementary work, maybe, since such children are as a rule immature mentally, although in some instances precocious in superficial brightness.”
A brief summary of the results of the mental and physical examinations of the 100 boys who form the basis of this paper is appended.
SUMMARY OF RESULTS.
Dull. Normal. Bright. Physiologically accelerated 0 10% 62% Systolic blood pressure above average for physiological age 0 19% 41% Average systolic blood pressure 95.5 mm. 104 mm. 108 mm. 1 Baldwin, Bird T. “Physical Growth and School Process.” U. S. Bureau of Education, Bulletin No. 10, 1914.
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