The subjects were tested with audiovisual and visual stimuli depicting male and female models at various stages of sexual development. The subjects were then asked questions regarding their sexual preference using standard polygraph techniques. It was found that both groups could suppress their responses when instructed to inhibit their stated sexual preference in the audiovisual series. When both groups were instructed to fake, or feign a spurious positive response to a non-preferred stimulus, the levels of arousal generated were variable and not significantly different from those obtained before instruction. Extraneous movement, measured by the lumbar pressure device, was notably greater in the three incest offenders included in the sample. Most of the polygraph data could not be related to the phallometric results. 12 tables, 8 figures, and 3 appendixes