Goring's Data as to Groups of Crime Committed Most Frequently by Those Mentally Deficient
| Nature of crimes | Total criminals | Mentally defective | Percentages of mental defectives among those committing various crimes | Percentages of general population committing the several offenses |
|---|---|---|---|---|
| Malicious damage to property | 55 | 22 | 40.00 | 0.406 |
| Stealing and burglary | 442 | 45 | 10.18 | 4.180 |
| Sexual offences | 101 | 13 | 12.87 | 0.199 |
| Violence to the person | 183 | 11 | 6.01 | 1.606 |
| Forgery, coining and fraud | 167 | 4 | 2.40 | 0.722 |
| Total | 948 | 95 | 10.00 | 7.203 |
Some very striking instances of recidivism on the part of the feeble-minded were summarized by Dr. Smalley in his evidence before the Royal Commission ([83]). He said:
“Against 130 out of 333 weak-minded prisoners who were unfit for ordinary penal discipline by reason of mental deficiency, no previous conviction had been recorded; but for this absence of record their nomadic habits might in part account. Against fifty-six 1 conviction had been recorded, against twenty-eight 2; the remainder varied from 4 to 105 convictions. About half had been convicted from 5 to 10 times.... Dr. Hamblin Smith, Medical Officer of Stafford Prison, as the result of a special inquiry into 100 mentally defective prisoners, found that 100 had a combined record of 1,104 convictions, or an average of 11 per prisoner, and this number was regarded as being below the actual truth. Ten of the prisoners had over 30 convictions. Dr. W. R. Dawson found that in the two prisons in Dublin 12.21 per cent. of the inmates were defectives. The average number of previous convictions for the females was 44.13. Many of them ran into hundreds, and one was in prison for the two-hundred and thirty-sixth time, and she was only twenty-nine years old.”
So far as I can discover nobody has directly attacked the specific problem, what percentage of individuals of a given degree of deficiency who are not under supervision, become legally delinquent at some time in their lives. A slight contribution to the empirical study of the problem is made in the reports of the follow-up work in connection with pupils formerly in special classes in the public schools which I reviewed in Chap. IV, f. We have also a telling report by Bullard of the New York Prison Association published by Moore in 1911 ([156]). It follows the records of 85 feeble-minded boys and men 16-29 years of age, paroled from the Elmira State Reformatory in 1904. The whereabouts of 3 were unknown and 2 died. Of the remaining eighty, 31 were arrested again and 6 others violated their parole. One was arrested 19 times in this short period.
The best approach to this problem of measuring the potential delinquency among deficients is afforded by Goring's four-fold table for calculating the correlation between deficiency and criminality in the male population of England and Wales (20, p. 259). By means of the annual data on first convictions of crime at different ages and the probable length of life among criminals and in the general population he has been able to predict a potential criminality on the part of 7.2% of the general male population. In other words, the best estimate seems to be that about 7 in every hundred males in England and Wales will be convicted of crime at some time in their lives. About 10% of the convicts in England for a series of years have been isolated in prison treatment because of deficiency. If we now also assume with him that 0.46% of the non-criminal population is mentally deficient, we arrive at the table which enables us to determine, on these assumptions, that it is most likely that 63% of the deficients will be convicted of crime at some time in their lives. If instead of taking this estimate of 10% of the criminals being deficient we had taken 20%, then the probability of a deficient individual being convicted of crime would rise to .77.
On the basis of our summary of tested delinquents in the last chapter it seems extremely conservative to suppose that 10% of the manifest and potential criminals are as deficient mentally as the lowest 1.5% of the general population. Even with this assumption we find that the chances would be 48 out of a hundred that a person of this degree of deficiency would be convicted of crime.
These estimates, I believe, afford a telling argument for the indefinite isolation of at least those who are in the lowest 0.5% mentally on the ground of their potential criminality, independently of any question of the danger to society from the hereditary transmission of the diathesis of deficient delinquency.
We have heard much in recent years of the particular danger of allowing the better grade of feeble-minded, especially the morons, to be abroad in the community. Time and again it is asserted that it is this class of deficients which is most likely to become delinquent. There is a widespread confusion here between the statement that criminals in absolute numbers are drawn more frequently from the moron class and the statement that morons are relatively more likely than imbeciles or idiots to become delinquent. To the first alternative there would be no objection since morons are much more frequent than the lower grades of deficiency. On the other hand if morons are relatively more likely to be delinquent than imbeciles, then we should expect those just above the morons in ability to be more likely than morons to be delinquent. The technical answer to the problem whether the lower grades of deficiency are more likely to become delinquent could be best reached by discovering the correlation of delinquency with the different grades of deficiency.
Goring's data throw some light on this question since he has found the correlation between grades of intelligence and the degree of recidivism and also between intelligence and the frequency of bad reports in the penal institutions where the convicts were held. In both cases the tendency is clear for the weak-minded and imbecile to be more frequently convicted and to be reported more frequently for bad conduct than for the higher grades of intelligence which he classifies as unintelligent, fairly intelligent and intelligent. The correlation coefficient with frequency of convictions relative to time out of prison is -.16 and with frequency of bad reports is -.33. The correlation ratios are slightly higher in both cases. On the other hand the more intelligent are likely to be given longer sentences, the correlation being +.10.[[33]] It might be contended that his distinction between the lowest grades of intelligence is not objective and not very clear; but that the general tendency of the regression lines would be reversed at the lower extreme seems very improbable. In other words there is some reason to suppose that, relative to their numbers, the idiots and imbeciles would be more likely to be delinquent than the more intelligent feeble-minded provided none was confined in an institution. No idiot and few, if any, imbeciles could survive honestly in any environment without assistance.