Chapter XIV. QUANTITATIVE DEFINITIONS OF THE BORDERLINE 304

A. DIFFERENT FORMS OF QUANTITATIVE DEFINITIONS 304

B. COMMON CHARACTERISTICS OF QUANTITATIVE DEFINITIONS 308

C. PRACTICAL ADVANTAGES OF THE PERCENTAGE METHOD 311

D. THEORETICAL ADVANTAGE OF THE PERCENTAGE METHOD WITH CHANGES 317 IN THE FORM OF THE DISTRIBUTIONS

BIBLIOGRAPHY ON TESTED DELINQUENTS 324

Other References Cited 329

APPENDICES 344

INDEX 353

LIST OF TABLES AND FIGURES

TABLES

I. Age distribution of deaths in the general population and of 30 feeble-minded in institutions

II. Mortality of institutional deficients in the United States 31 compared with the general population

III. Test borderlines with randomly selected Minneapolis 89 15-year-olds

IV. Results with the Binet tests for mental ages XI and XII 98 (1908 series)

V. Percentages of mentally retarded children as tested with the 106 Binet 1908 Scale

VI. Mental retardation of children as tested with the Binet 1911 111 Scale

VII. Borderlines with the Point Scale 115

VIII. Test ages of the Glen Lake group of delinquent boys 124

IX. Intellectual development relative to life-ages and school 125 positions among the delinquent boys of Glen Lake

X. Binet 1911 tests of boys consecutively admitted to the 151 Detention Home at Thorn Hill, Allegheny County

XI. Frequency of tested deficiency among over 9000 delinquents 159

XII. Age and grade distribution of elementary school pupils in 178 Minneapolis

XIII. School retardation of Minneapolis delinquents and elementary 179 school pupils

XIV. Indices of frequency and amount of school retardation for 183 Minneapolis delinquents and elementary school pupils

XV. Percentage of pupils 12 and 13 years of age most seriously 193 retarded in school

XVI. School position of delinquents at Glen Lake relative to 204 their intellectual development

XVII. Goring's data as to the percentage of mental defectives 213 among men convicted of various offenses

XVIII. Goring's data as to groups of crimes committed most 214 frequently by those mentally deficient

XIX. Four-fold correlation table for juvenile delinquency and 222 deficiency in Minneapolis

XX. Average Intelligence Quotients of children of different 296 ability

XXI. Test records with random 15-year-olds 344

XXII. Test records with delinquents at the Glen Lake Farm School 349

FIGURES

1. Mortality among feeble-minded in institutions compared with 32 the general population

2. School retardation of Minneapolis delinquents compared with 180 elementary school boys

3. Hypothetical development curves (normal distributions) 253

4. The question of equivalence of year units 265

5. Hypothetical development curves (changing form of 277 distribution.)

6. Tests of the development of memory processes. Medians at 285 each age for the central tendencies of the tests

7. Different types of development. Medians at each age for the 286 central tendencies of the tests

8. Forty tests of development. Distribution at each age for the 287 central tendencies of the tests

9. Relative positions at each age of the median and of 299 corresponding bright and retarded children with the Form Board Test

DEFICIENCY AND DELINQUENCY

PREFACE

In undertaking in 1912 to examine the mental development of delinquents for the clinic started and supported by the Juvenile Protective League of Minneapolis, in connection with the Juvenile Court, I soon became convinced that a safer method for evaluating the limit of feeble-mindedness with tests was more needed than masses of new data. The researches that have been published in the past three years do not seem to have changed this situation. Numerous studies with psychological tests are already available, but they generally treat of average rather than borderline conditions. In the field of delinquency the work of testing has been carried on with especial activity. Here, as well as elsewhere, the conclusions seem likely to be misleading unless social workers better appreciate the real place of mental tests, their value and their limitations.

The tables of a few hundred juvenile delinquents and school children examined in Minneapolis, which are presented in this book, indicate the occasion rather than the aim of the present study. The purpose is mainly to help clear the ground for other work with mental tests, and especially to put the determination of feeble-mindedness by objective examination with the Binet or other scales on what seems to me a sounder basis. Furthermore, the results of objective testing which have been so rapidly accumulating in the field of delinquency need to be assembled and reorganized in order to avoid confusion. It is especially desirable to discover a conservative basis for objective diagnosis of deficient intellectual capacity in order to prevent very useful testing systems from becoming unjustly discredited and to preserve the advance that has been made.

The work out of which this monograph grew was begun through the encouragement of Judge Edward F. Waite of the Hennepin County Juvenile Court. His earnest co-operation and my interest in the field of mental testing has led me to continue the study. Judge Waite's insight into his court problems resulted in the early organization of a Juvenile Court clinic (_153_, _170_) in Minneapolis. The clinic is in charge of Dr. Harris Dana Newkirk, who has contributed materially to this study by his thorough medical examination of each of the cases brought to him. To the staff at the probation office I am also much indebted.

The earnest help of Superintendent D. C. MacKenzie, of the Glen Lake Farm School for the juvenile delinquents of Hennepin County, made a close study of our most interesting group of boys much more profitable personally than I have shown here. For detailed expert work in tabulation and in examinations I wish to express my thanks to my advanced students, a half dozen of whom have contributed materially to the data of this book.

JAMES BURT MINER.

Carnegie Institute of Technology Pittsburgh, Pa.