Archives of Sexual Behavior, Vol. 5, No. 4, 1976

The Intelligence of Rapists

Carol F. Ruff, M.A., 1 Donald I. Templer, Ph.D., 2 and Joyce L. Ayers, M.A. 3

IQs o f rapists were compared to IQs o f nonrapist prisoners convicted o f violent crimes and nonrapist prisoners convicted o f nonviolent crimes. Subjects were 136 male convicted felons in the Kentucky State Penitentiary. Determination of violent vs. nonviolent crimes other than rape was made upon consultation with a Kentucky Commonwealth Attorney. The results revealed significantly lower IQs for rapists compared to nonrapists convicted o f violent crimes and compared to heterogeneous nonrapist convicts. The present research supports the findings o f Karacan and co-workers, indicating a general tendency for rapists to have lower IQs than other convicted prisoners.

KEY WORDS: rapist; prisoners; crimes -- violent; crimes -- nonviolent; IQ; sex.

INTRODUCTION

The research purpose was to determine the intelligence of rapists in com- parison to that of other convicted felons. Clinical reports (Allen, 1969; Randell, 1973) suggest that rapists tend to be of low intelligence. Gebhard et al. (1965) found that rapists tend to have IQs that are below average and less than those of exhibitionists, incest offenders, and homosexual offenders of children. Yet these authors presented neither mean IQs nor statistical analyses.

Apparently there have been only two studies in which the comparative intelligence of rapists and heterogeneous convicts has been determined. Karacan et al. (1974) reported that Quick Test IQs of rapists were significantly lower than those of prison control subjects. However, Perdue and Lester (1972) found that the Wechsler Adult Intelligence Scale (WAIS) IQs of rapists did not signifi-

1 Chief Psychologist, Western State Hospital, Hopkinsville, Kentucky. 2 Chief Psychologist, Waterford Hospital, St. John's, Newfoundland, Canada. 3 Staff Psychologist, Western State Hospital, Hopkinsville, Kentucky.

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328 Ruff, Templet, and Ayers

cantly differ from those of inmates convicted of aggressive, nonsexual crimes. Because of the different results, the composite picture derived from these two studies is not conclusive. Furthermore, in both these studies the matter of IQ was only tangentially related to the main purpose of the research.

The present research was initiated to bring the question of the IQs of rapists into a less inconclusive perspective. The authors considered the pos- sibility that the different results of the research of Karacan and co-workers and that of Perdue and Lester could be explained by the former investigators having compared the rapists with heterogeneous, nonrapist convicts and the latter having compared the rapists with violent, nonrapist convicts. In the present research, both comparisons were made.

METHOD

The subjects were 136 male convicted felons in the Kentucky State Penitentiary located at Eddyville, Kentucky. All subjects were inmates who had been referred for psychological testing by a rehabilitation counselor within the last 2 years.

The ten rapists had a mean age of 34.2 years, with SD = 8.73 years. The 126 nonrapists had a mean age of 30.28 (SD 8.12).

Determination of violent vs. nonviolent crimes other than rape was made upon consultation with the Commonwealth Attorney who represents the Ken- tucky counties of Christian, Trigg, and Lyon. Violent crimes include such crimes as armed robbery, arson, assault, escape, inciting to riot, kidnapping, man- slaughter, malicious cutting and wounding, malicious shooting and wounding, murder, resisting arrest, riot, terroristic threatening, and wanton endangerment. Nonviolent crimes include such crimes as bigamy, burglary, forgery, illegal sale of narcotics, fraud, incest, perjury, receiving stolen property, and theft.

If an inmate had been convicted of both a violent and a nonviolent crime, he was classified as a violent criminal. Seventy-five of the 126 inmates were classified as violent criminals.

RESULTS AND DISCUSSION

The Full Scale WAIS IQ mean and standard deviation were 83.00 and 12.02, respectively, for the ten rapists. For the 126 nonrapists, the IQ mean and standard deviation were 94.10 and 16.75 (t = 2.07~v < 0.025, one-tailed). The 75 violent nonrapists obtained a WAIS mean of 95.04 (SD = 19.58), and their mean also differed significantly (t = 1.93,p < 0.05, one-tailed) from that of the rapists.

The Intelligence of Rapists 329

There was a nonsignificant trend (X 2 = 1.12) for the 34 Blacks to have a greater proportion of rapists than the 97 Whites. There were five Black and five White rapists. However, it does not appear that the lower IQs of rapists can be understood by a Black-White interpretation. Such an explanation would have appeared plausible if the mean IQs of rapists and nonrapists had been the same for both the Blacks and the Whites. However, the actual situation was that the mean IQ discrepancy of Black rapists (78.00) and nonrapists (87.38) was very similar to the discrepancy between White rapists (88.00) and nonrapists (96.58).

The present research converges with the study of Karacan and co-workers to point toward a general tendency for rapists to have lower IQs than other convicted prisoners. Nevertheless, because of the research of Perdue and Lester, it would appear that such a difference may not exist in all correctional settings.

REFERENCES

Allen, C. (1969). A Textbook of Psychosexual Disorders, Oxford University Press, London. Gebhard, P., Gagnon, J. H., Pomeroy, W. B., and Christenson, H. T. (1965). Sex Offenders,

Hoeber, New York. Karacan, I., Williams, R. L., Guerrero, M. W., Solis, P. J., Thornby, J. I., and Hursch, C. J.

(1974). Nocturnal penile tumescence and sleep of convicted rapists and other pris- oners. Arch. Sex. Behav. 3: 19-25.

Perdue, W. C., and Lester, D. (1972). Personality characteristics of rapists. Percept. Motor Skills 35: 514.

Randell, J. (1973). Sexual Variations, Priory Press, London.