The light source illuminates the capillary bed of the clitoral tissue and the blood circulating within it.
The clitoral photoplethysmograph is placed by the participant between the labia minora; the light detector is oriented toward the clitoris.
[citation needed] Gerritsen[1] found clitoral photoplethysmography to be a valid and sensitive tool for measuring female genital response.
In contrast to vaginal photoplethysmography, clitoral photoplethysmographs are sensitive to the inhibition of sexual response.
Some researchers have posited that the procedure might be a viable instrument for assessing female sex offenders.