An investigation of the relationship between intelligence and various aspects of criminal behavior

The question of the relationship between intelligence and criminality has usually been approached from the standpoint of causality. This approach leads to a multiplicity of unanswered questions which are almost impossible to investigate objectively. The present study obviates these problems by approaching the problem from the standpoint of the relationship between intelligence and the behavior of individuals convicted of felonious behavior. In order to investigate this relationship, a sample of felony inmates was extracted from the central records of the Texas Department of Corrections, Huntsville, Texas. The sample consisted of 2,592 retardates, (IQ's below 70), 4,000 normals (IQ’s ranging from 85-115), and 402 superiors (IQ's above 115). These three groups were tested for significant differences with respect to seventy-three dependent variables, including demographic information, and criminal and social history. Data on discrete variables were analyzed by using chi-square procedure while continuous variables were analyzed by the t-test. In all cases, differences were considered to be significant at the .05 level of confidence. The following is an enumeration of some of the con- elusions drawn from the data. 1. The retarded group has a higher percentage of Negroes and Latins than the more intelligent groups. This is probably the result of a culturally biased intelligence test combined with cultural deprivation prevalent among the lower socio-economic groups. 2. Retardates have the lowest educational achievement among the three groups while the superiors have the highest. This would seem to indicate that the retardate is handicapped in a rehabilitation program that stresses academic achievement. 3. The data indicate that retardates are more likely to be convicted of crimes which require (1) lack of ability to plan a course of action, (2) lack of executive ability, and (3) poor emotional control. These tend to be offenses against persons. 4. The data suggest that retardates tend to receive fewer probations than the more intelligent groups. 5. Using the variables of trustee status, number of solitary confinements, and escapes as criteria, the data suggest that retardates adjust to prison life about as well as the more intelligent groups. 6. Using such variables as the number of offenses, number of confinements, parole violations and habitual and subsequent offenses as criteria, it was concluded that the more intelligent groups tend to recidivate more often than retardates. This, however, may be a function of factors other than intelligence, such as geographic mobility and criminal justice practices. 7. Normals have more co-defendants than both retardates and. superiors. This would indicate that the latter two groups tend to commit their offenses alone. In the case of the retardate, it is possible that he is more involved with other offenders than the data show, but he might have been the only one apprehended in the group. 8. The data suggest that retardates generally have lower percentages with regard to those variables which require a good deal of geographic mobility on the part of the subject.