“…The procedure is relatively easy to use, and it can provide two simultaneous measures (vaginal pressure pulse from AC amplification of the signal from the photosensor, and vaginal blood volume from DC amplification) that consistently increase during sexual stimulation. For example, increases in vaginal blood volume have been recorded during erotic films (Geer, Morokof, and Greenwood, 1974;Henson, Rubin, and Henson, 1979;Hoon, 1976, 1977;van Dam, Honnebler, van Zalinge, and Barendregt, 1976;Wincze, Hoon, and Hoon, 1976, 1977, during erotic audio-recordings and sexual fantasy (Heiman, 1976(Heiman, , 1977, and during masturbation (Geer and Quartararo, 1976;van Dam et a., 1976). Similarly, vaginal pressure pulse has been demonstrated to increase during erotic films (Geer et al, 1974;Henson et a., 1979;Lawson, 1976, 1978), during audio-recordings and sexual fantasy (Gillan, 1976;Heiman, 1976Heiman, , 1977 and during masturbation (Geer and Quartararo, 1976;Gillan, 1976;Sarrel, Foddy, and McKinnon, 1977 (Heiman, 1976(Heiman, , 1977Henson et al, 1979).…”