Intellectual Deficits among Incoming Federally Sentenced Men and Women Offenders: Prevalence, Profiles, and Outcomes

Research Highlights

Offenders in CSC have IQs in the average range. Lower IQ is associated with more misconducts and revocations.

Why we did this study

Intellectual deficits (ID) involves impairment of mental abilities that affects adaptive functioning. People with ID are thought to be over-represented in the criminal justice system but firm rates of impairment among offenders have been difficult to estimate. Information on the rates of ID among federal offenders is required to plan for appropriate services.

What we did

This study assessed the prevalence of ID among 4,396 men and 292 women offenders entering federal custody using a standardized measure of IQ (General Ability Measure for Adults t (GAMA)) and examined the association between IQ level with key offender characteristics and correctional outcomes.

What we found

Results indicated that 2.8% of men scored below 70 IQ, rates roughly similar to those in the general population. A further 7.3% scored in the borderline range (70-79). Federally-sentenced women were more likely to suffer ID than federal men. Almost 6% of incoming women have an IQ below 70 and 12.7 % score in the borderline range. Thus twice as many women in CSC are within the intellectually impaired ranges than is found in the general population.

The results link lower IQ scores to lower educational achievement, unstable employment, substance abuse, and symptoms of ADHD for both men and women. Offenders with lower IQ had higher overall criminal risk and criminogenic need ratings than those in the unimpaired groups.

Lower IQ was associated with more transfers to segregation and institutional charges for both men and women. Relative to men with average or higher IQs, men with lower IQs were more likely to be instigators of security incidents, but not more likely to be victims. Women with lower IQs were both more likely to be victims and instigators. Although completion rates for correctional program participants who have ID were lower than for those in the average or above average IQ categories, the rates are still quite high at 80%. Offenders with lower IQ were less likely to be granted discretionary release. On release, IQ was related to men’s revocations even when age, risk and need levels, and substance abuse rating were considered. Revocation rates were low for women, but the same pattern linking low IQ to poorer outcomes was found. Notably, higher IQ was a protective factor for women; none of the women in the above average range returned to custody during the follow-up period. A small qualitative component of the study highlighted the types of assistance provided to offenders within the lowest IQ bracket and the challenges they experienced after release.

What it means

Men with lower IQs require assistance with educational and employment training and aspects of community function while the lower functioning women require assistance with all aspects of their functioning. This is especially true for Aboriginal women whose rates of impairment were significantly higher than non-Aboriginal women. The type of skills taught in CSC’s correctional programs, and the pedagogical techniques applied, are consistent with effective approaches in special education and the targets of the correctional programs, with their focus on self regulation skills, are appropriate to the needs of the offenders with lower IQ that were identified in this research.

For more information

Stewart, Wilton, Kelly, Nolan, & Talisman (2016). Intellectual deficits among incoming federally sentenced men and women offenders: Prevalence, profiles, outcomes. (Research Report R-367). Ottawa, Ontario: Correctional Service of Canada

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