Penile Plethysmography
![[photo of instrument]](images/ei/mercuryinrubber.jpg)
"Originally described by Fisher and colleagues (1965), the first circumferential measure, the mercury-in-rubber strain gauge, was adapted from a similar transducer used by Shapiro and Cohen (1965). The device consists of a hollow rubber tube filled with mercury and sealed at the ends with platinum electrodes. The operation of the mercury-in-rubber strain gauge depends upon penile circumference changes that cause the rubber tube to stretch or shorten, thus altering the cross-sectional area of the column of mercury within the tube. The resistance of the mercury inside the tube varies directly with its cross-sectional area, which in turn is reflective of changes in the circumference of the penis. Variations of the mercury-in-rubber gauge have been described by Bancroft et al. (1966), Jovanovic (1967), and Karacan (1969)."
From Janssen, E., Prause, N., & Geer, J. (2007). The sexual response. In J. T. Cacioppo, L. G. Tassinary, & G. G. Berntson (Eds.), Handbook of Psychophysiology, 3rd ed. New York: Cambridge University Press.