Chapter I: Front Matter

A. THE MEANING OF INTELLECTUAL DEFICIENCY 10

B. FORMS OF MENTAL DEFICIENCY NOT YET DISCOVERABLE BY TESTS 14

C. DOUBTFUL INTELLECTS ACCOMPANIED BY DELINQUENCY PRESUMED 18
DEFICIENT

Chapter III. THE PERCENTAGE DEFINITION OF INTELLECTUAL DEFICIENCY 20

A. THE DEFINITION 20

B. THE ASSUMPTIONS OF A QUANTITATIVE DEFINITION 21

(a) Deficiency is a Difference in Degree not in Kind 21

(b) As to the Variation in the Frequency of Deficiency at 23
Different Ages

(c) As to the Number of Deficients not Detected by Tests 34

(d) Allowance May be Made for Variability 40

Chapter IV. WHAT PERCENTAGE IS FEEBLE-MINDED 47

A. KINDS OF SOCIAL CARE CONTEMPLATED 47

B. ESTIMATES OF THE SCHOOL POPULATION VERSUS THE GENERAL 48
POPULATION

C. DESIRABLE VERSUS IMMEDIATELY ADVISABLE SOCIAL CARE 51

D. PERCENTAGES SUGGESTED TO HARMONIZE THE ESTIMATES 52

E. COMPARISON WITH IMPORTANT ESTIMATES 56

F. THE ABILITY OF THE MENTALLY RETARDED ESPECIALLY THOSE 74
RECEIVING SPECIAL TRAINING

Chapter V. ADAPTING THE PERCENTAGE DEFINITION TO THE BINET SCALE 82

A. THE BORDER REGION FOR THE MATURE 82

(a) Indication from a Random Group 82

(b) The Present Tendency Among Examiners 95

B. THE BORDER REGION FOR THE IMMATURE 104

(a) For the Binet 1908 Scale 104

(b) Data for Other Developmental Scales 110

(c) The Change in Interpreting the Borderline for the 116
Immature

Chapter VI. DELINQUENTS TESTING DEFICIENT 122

A. AT THE GLEN FARM SCHOOL FOR BOYS, HENNEPIN COUNTY, 122
MINNESOTA

B. COMPARISON OF TESTED DEFICIENCY AMONG TYPICAL GROUPS OF 127
DELINQUENTS

(a) Women and Girl Delinquents in State Institutions 128

(b) Women and Girl Delinquents in Country and City 134
Institutions

(c) Men and Boy Delinquents in State Institutions 141

(d) Men and Boy Delinquents in County and City 148
Institutions

C. SUMMARY OF TESTED DEFICIENCY AMONG DELINQUENTS 158

Chapter VII. CHECKING THE BINET DIAGNOSIS BY OTHER METHODS 170

Chapter VIII. SCHOOL RETARDATION AMONG DELINQUENTS 177

A. IN MINNEAPOLIS 177

B. SCHOOL RETARDATION AMONG OTHER GROUPS OF DELINQUENTS 185

Chapter IX. COMPARISON OF THE SCHOOL TEST AND THE BINET TEST 189

A. PRACTICAL USES OF THE SCHOOL TEST 190

(a) Estimating the Frequency of Deficiency by School 190
Retardation

(b) School Retardation as a Warning of the Need for 194
Examination

(c) School Success as a Check on the Binet Diagnosis 197

B. CHECKING DEFICIENCY AMONG DELINQUENTS BY THE SCHOOL TEST 199

Chapter X. BAD SCHOOL ADJUSTMENT AS A CAUSE OF DELINQUENCY 203

Chapter XI. DEFICIENCY AS A CAUSE OF DELINQUENCY 210

A. THE CHANCES OF THE MENTALLY DEFICIENT BECOMING DELINQUENT 211

B. THE CORRELATION OF DEFICIENCY AND DELINQUENCY 218

C. THE CAUSES OF DELINQUENCY 224

(a) Constitutional Factors 224

(b) External Factors 225

(c) Weighing Heredity Against Environment 229

(d) The Criminal Diathesis 234

Chapter XII. SUMMARY AND SUGGESTIONS 239