Most women report reliably experiencing orgasm from masturbation, but a smaller proportion of women report regularly experiencing orgasm from intercourse. Research suggests that concurrent clitoral stimulation during intercourse increases the likelihood of orgasm, yet most surveys of orgasm during intercourse leave unspecified whether vaginal intercourse does or does not include concurrent clitoral stimulation (assisted intercourse or unassisted intercourse, respectively). Using an online sample of 1569 men and 1478 women, we tested whether phrasing of questions about the occurrence of orgasm in intercourse modulates women's reported frequency and men's estimates of women's frequency of orgasm in intercourse. Participants provided estimates of orgasm when asked explicitly about intercourse with stimulation unspecified, assisted intercourse, and unassisted intercourse. Women's reports of orgasm occurrence were highest in response to assisted intercourse (51-60%), second highest in response to intercourse with clitoral stimulation unspecified (31-40%), and lowest in response to unassisted intercourse (21-30%). Men's estimates of women's orgasms were highest in response to assisted intercourse (61-70%), and lowest in response to unassisted intercourse (41-50%); in both conditions, men's estimates were significantly higher than women's reports. When clitoral stimulation was unspecified, women interpreted "orgasm in intercourse" in three ways: as from intercourse alone, as including concurrent clitoral stimulation though it was unspecified, or as an average of assisted and unassisted intercourse. Taken together, these results demonstrate that the phrasing of questions about women's orgasm produces markedly different orgasm estimates, and suggest that concurrent clitoral stimulation increases the likelihood of women experiencing orgasm in intercourse.
Keywords: Clitoral stimulation; Female orgasm; Intercourse; Masturbation; Sex difference.