Sex offender treatment programs usually assess sexual attraction by attaching a device called a plethysmograph to the individualís penis. The plethysmograph measures and records penile erection as various visual or auditory stimuli are presented. These stimuli may be slides or videos of naked children or adults, and auditory stimuli may be recorded descriptions of sexual acts (consenting or coerced) involving adults and/or children.7
The plethysmograph is used not only to identify those offenders who are sexually attracted to minors, but also to determine whether their attraction has been reduced or eliminated by treatment.
Some professionals write that the plethysmograph is commonly used incorrectly for diagnosis and treatment decisions.8