An Analysis of Four Sexual Offenders' Arousal in the Natural Environment Through the Use of a Portable Penile Plethysmograph

We report the development of a technology for measuring sexual arousal in the natural environment. Experiment 1 demonstrated that levels of sexual arousal obtained in the laboratory when a participant was wearing underwear and trousers were similar to arousal levels obtained without underwear and trousers. In Experiment 2, four sexual offenders' arousal was measured in the natural environment using a portable penile plethysmograph. Measures were taken in three different settings: a setting in which only adults were present, a setting with children present, and a setting with no person other than the data collector present. In each setting, arousal was measured when the data collector was both near and away from the offender. For three of four offenders, pattems of arousal were consistent with previous laboratory assessments and/or previous offenses. Moreover, arousal was greatest when the data collector was away from the participant.