Deficiency and Delinquency: An Interpretation of Mental Testing

by James Burt Miner

To begin with the lowest group of the feeble-minded, we should consider those whom the state might be clearly justified in isolating indefinitely on the basis of their tested lack of intellectual capacity, the social isolation group. For purposes of comparison let us place this degree of intellectual ability as that possessed by the lowest 0.5% at fifteen years of age. Above these let us estimate a group of uncertain cases so far as isolation is concerned, but cases which the diagnostician would be justified in regarding as intellectually deficient enough to justify sending to special local schools for training the feeble-minded. After special training the majority of these cases might be expected to require social assistance indefinitely. They would form the social assistance group. Isolation would be justified for none of them on the basis of their test records alone. Those in this group who were persistent delinquents would, by that additional fact, fall into the lowest group so far as social care is concerned. Let us estimate this social assistance group tentatively as the next 1.0% at fifteen years of age.

These estimates have been made as at fifteen years of age since the effect of the excessive mortality especially among the isolation group is uncertain and may need to be allowed for in a discussion of the percentage deficient at different ages. If the mortality were as great as has been described among institutional cases in the previous chapter, a rough estimate of the percentage intellectually deficient in the general population places it at less than 0.5%. This estimate may be made by using the estimated deficiency at the median age of those under 15 years of age and at the median age of those 15 years of age and over. According to the age distribution of the 1910 census, there were 32% under 15 years with a median age of 6 years. At age six 0.67% would be presumed as low as 0.50% at 15 years. The older group (68% of the population) has a median age of 32 with a corresponding percentage in the isolation group at that age of 0.30%, after allowing for differences in mortality on the plan indicated in Table II. This rough estimate for the lowest group indicates that 0.42% of the general population would be of as low a degree of intellectual capacity as the lowest 0.5% at 15 years. Our plan presumes, therefore, that between 0.4% and 0.5% of the population are unable to pass their entire lives outside of institutions under ordinary conditions; i. e., make an honest living and live within the law even with social assistance and supervision.

The corresponding estimate for those requiring only social assistance would be between 0.8% and 1.0% of the general population above the lowest group. This might vary from approximately 1.34% at 6 years to 0.59% at 32, the median age for those over 14 years. Since the mortality is probably less among deficients not in institutions, as they average higher in ability, the changes in the percentages are probably extreme estimates. We should keep in mind, however, the possibility that with the excessive death rate the lowest 1.0% at 15 may mean an ability corresponding to the lowest 1.34% at 6 years and the lowest 0.60% at 32 years.

The next higher group in intellectual ability is so high as not to require social assistance outside of school. When we ask how large a per cent. we should be justified in placing in this group and separating merely for special instruction in school, we reach a condition which is at present so ill-defined even in the minds of educators that it seems best to fall back on the general advice that our school systems should provide just as nearly individual instruction as the public purse and managing genius can devise. Mannheim, Germany, for example, takes care of 18 per cent. outside of its regular school classes. The ideal is individual instruction for all. School authorities would be justified in providing special instruction for every degree of mental ability, if the cost would not restrict other more important social undertakings. This less degree of retardation in the group needing only school assistance should not, however, be classed as feeble-minded. We shall see later the percentages for which some authorities have considered it already advisable to provide special school instruction. We need not attempt to estimate the size of this group, as it is beyond the limit of feeble-mindedness.

The purely conative cases are not taken care of in the above estimates, which are intended for tested deficients. If the conative cases unaccompanied by intellectual deficiency should be regarded as frequent enough to replace those in the social assistance group who ultimately care for themselves, plus those subtracted by the excessive death rate, we would have a total of 1.5% of the general population feeble-minded enough to warrant social care of some sort. About 0.5% might justly be isolated. The reasonableness of this program can be judged by comparison with authoritative estimates now to be reviewed. The problem here is whether this is an unreasonable program for the diagnostician to assume as scientifically justified, remembering that these estimates are for tested deficients at 15 years of age and do not include purely conative cases which might occur above these intellectual borderlines.

E. Comparison With Important Estimates

The Social Isolation Group. We are now ready to consider some of the important estimates which throw light upon the reasonableness of the percentages we have named. First, what percentage would we be justified in socially isolating? In the United States Census Report on the Insane and Feeble-Minded in Institutions in 1910, we find that the number then actually in institutions for feeble-minded was only about 0.02% of the population. At the most frequent ages this rises to about 0.05%. It is evident that the number actually isolated is of little significance except as a check on the estimates. The report, however, refers to the special estimate made by the public authorities in Massachusetts which also included feeble-minded in state hospitals for the insane, other asylums, those reported by the overseers of the poor and those enumerated in the general population. The U. S. report says: “The census was not regarded as being complete, but it is of interest to note that if the number of feeble-minded in proportion to the total population was the same for the entire United States as it was in Massachusetts according to this census, the total number of feeble-minded would be over 200,000. Probably this may be regarded as a conservative estimate of the number of feeble-minded in the United States and would indicate that not over one-tenth of the feeble-minded are being cared for in special institutions” (205, p. 183). This estimate, which thus amounts to about 0.2%, may probably be considered as a reasonable program of expansion from the institutional viewpoint. The diagnostician who is considering the individual and not the mass must supplement it by considering who should be isolated if facilities were available. If the census bureau can contemplate institutional care for ten times those at present thus provided for, it gives us some indication of a reasonable limit as to the increase in institutional care that can be assumed to be reasonably contemplated at present.

Dr. W. D. Cornell, director of medical inspection of the Philadelphia public schools, after the personal examination of those cases which in the opinion of the teachers should be sent to institutions, places the “institution cases” at a minimum of 15 per 10,000 school children. He adds: “The number of evidently feeble-minded above 6 years of age may be said to be 1 to every 500 of the population. These figures are conservative and have been accepted by experts for years.” This then is the minimum estimate and quite clearly refers to institutional cases.

A committee of the Public School Alliance of New Orleans, of which Prof. David Spence Hill was chairman, reported in 1913 a careful census of the public school children in that city the previous year made by the teachers in co-operation with the Newcomb Laboratory of Psychology and Education. Each teacher was asked to state her opinion as to how many in her room were “feeble-minded or insane children who should be under institutional or home care, rather than in the public schools.” Also the number of backward children not in the above class “who urgently need special educational methods in special classes within the special schools.” About a fifth of the total of the 38,000 school children in the city are colored. The grand total showed 0.28% in the first class mentioned above, and 7.7% in the second. Speaking of those “thought by teachers to be feeble-minded” and needing institutional care the report says:

“The figure 0.28 of 1% coincides exactly with the estimate of the Philadelphia Teachers' Association made in 1909 in a census of 150,000 school children. Secondly, while the teacher's estimates are open to revision, nevertheless her judgment, as inevitably evidenced in her attitude toward the child, is the practically effective judgment” (157, p. 6). It is a well-known fact that teachers tend to underestimate the frequency of mental deficiency, so that it would certainly be a matter of regret if this were to continue to be the “practically effective judgment.”