Sexual arousal
Sexual arousal results in a combination of physiological and psychological factors, like genital sexual response and subjective experience of sexual arousal. The degree to which genital and subjective sexual response correspond is termed "concordance". Research has shown a reliable gender difference in concordance of sexual arousal, such that men have a higher level of concordance between genital and subjective sexual responding than women do. Some researchers argue that this gender difference can be attributed to the type of method used to assess genital responding in women. There may be a difference in women's ability to perceive internal versus external genital engorgement subjectively, as measured by vaginal photoplethysmography (VPG) and thermography respectively. Chivers and colleagues found that men's and women's concordance was more similar when thermography was used as a measure of genital sexual arousal than when VPG was used. However, few studies using thermography have been conducted and further research is required to determine whether the gender difference in concordance is a measurement artifact or a true phenomenon.