From New Scientist:


Women who thought their responses might be read said they had had an average of 2.6 sexual partners, compared with 3.4 partners for those who thought their answers were anonymous. But those who thought they would be caught out by the polygraph reported an average of 4.4 partners.

In contrast, men's answers did not vary significantly. Those attached to the lie-detector reported an average of 4.0 partners compared with 3.7 for men who thought their answers would be read.

Fisher and Alexander (Journal of Sex Research, vol 40, p 27) surveyed over 200 unmarried, heterosexual college students aged 18 to 25. The disparity between women and men is due to young males' relative lack of appeal.