Male Sexual Arousal and the Law of Initial Value

Penile circumference was measured for 24 men before and during exposure to erotic material of matched content presented in 5 modes: film, slides, spoken, written, and fantasy. Stimulation in each case involved 8, 2-min episodes graded in content from low to high heterosexual arousal value. Three indices were used to test for the Law of Initial Value (LIV). No consistent evidence was obtained that stimulation levels or change scores varied systematically with prestimulus baseline values. The data indicate that male sexual arousal can be investigated without the need to adjust change scores to take into account initial value, at least when guided relaxation has been used to stabilize basal rates.