Responses to treatment for sex offenders with intellectual disability: a comparison of men with 1- and 2-year probation sentences.
Two years of probation plus group therapy cuts repeat sex offenses in half for men with intellectual disability compared to one year.
01Research in Context
What this study did
The team worked with the adult men who had both intellectual disability and a sex-offense history.
Half got one year of probation plus weekly group therapy. The other half got two years of probation with the same therapy.
Both groups learned about taking responsibility, understanding victim harm, and keeping future victims safe.
What they found
After two years, the longer-probation group showed much better scores on tests of pro-offending attitudes.
Only a large share of the two-year group committed another sexual offense, compared to a large share of the one-year group.
The extra year of support and supervision made the biggest difference.
How this fits with other research
Murphy et al. (2007) later tested CBT alone without probation. They still saw attitude gains, but behavior change was spotty. This suggests probation plus therapy works better than therapy alone.
Sappok et al. (2024) ran a virtual sex-ed group for autistic adults without ID. Their high satisfaction ratings show adults with developmental differences will engage in sexuality groups, backing up the 1998 finding that group format works.
Kok et al. (2026) found that youth behavior gains often fade after treatment ends. The 1998 study shows longer supervision may prevent this drop-off in adults.
Why it matters
If you treat adults with ID and sexual offense history, plan for at least two years of active support. Combine group therapy with ongoing supervision instead of brief programs. Track both attitude scores and real-world safety behaviors to see if gains stick.
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02At a glance
03Original abstract
The present study compares the responses to treatment of sex offenders with intellectual disability receiving 1- and 2-year probationary sentences. There were seven subjects in each group. There were no differences between subjects with regard to age, IQ or previous offences. All subjects received group treatment which addressed issues of: denial, minimization and responsibility for the offence; harm done to the victim; behaviour consistent with offending; and victim awareness and confidentiality. The subjects were assessed on a standard questionnaire designed to assess attitudes consistent with sex offending. All subjects were convicted of either indecent exposure or offences against children. There was a significant difference between the groups at the end of the probation period with subjects sentenced to 2 years' probation showing greater improvement. Subjects receiving 1 years' probation retained a number of attitudes consistent with denial and minimization of their offence. Furthermore, follow-up data underlined the poorer response to treatment for the 1-year probation group in terms of re-offending rates and assessment of attitudes consistent with sex offending. The authors recommend that a court order for a 1-year period of probation with treatment is of little value when dealing with sex offenders with intellectual disability. Rather, a period of at least 2 years' probation with a treatment recommendation is suggested.
Journal of intellectual disability research : JIDR, 1998 · doi:10.1046/j.1365-2788.1998.00147.x