Penile plethysmograph (PPG). The PPG is a penile plethysmograph system consisting of integrated software, stimulus materials, hardware, and clinical interpretation and methodology. The PPG measures the client's sexual response pattern and the extent of deviant arousal. It simultaneously monitors the client's penile responses, respirations, and galvanic skin response. The system also has built-in anti-faking methodology to enhance the internal validity of the data. Dr. Hawks contracts to BTI in
Salt Lake City to complete PPGs.