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Note: What follows is an adaptation of a previous article I wrote for the web site Science Of Relationships.
Casual sex, women like it.
Men are more interested and likely to engage in casual sex than women, right? From film, to music, to magazines-- it's one of those things everyone (seemingly) "knows" about the respective sexes that is pervasive in popular culture. Visit your local bookstore's self-help section and you're likely to a see volumes (for example, the "Mars and Venus" series) dedicated to understanding how suchsex differences should be understood if we're to experience relational and sexual bliss.
New research, however, published in the Journal of Personality and Social Psychology shows that when great pleasure is expected, women are just as likely as men to say "YES" to casual sex. The innovative set of studies(1) carried out by Dr. Terri Conley at the University of Michigan support predictions consistent with Pleasure Theory(2). This perspective argues that sexual reproduction is a bi-product of sexual pleasure, rather than vice-versa. We've evolved to seek pleasurable experiences; if enough people are having pleasure through sex, then the species will reproduce as a consequence. And herein lies perhaps the most pertinent sex difference of all-- women generally have a more difficult time achieving sexual pleasure from a casual encounter than men. For example, recent work has shown that women orgasm only 35% as often as men do in first-time sexual encounters(3).
Conley's work suggests that when the conditions are right, women are more similar to men in how they respond to an offer for casual sex than previously has been thought. The greatest contribution to explaining if a woman will accept an offer for casual sex is her perception of how sexually pleasurable the encounter will be. Because men orgasm more easily, they tend to be less picky about whom the casual sex is with. For women however, the sexual prowess of the person offering the sex is highly relevant. If she doesn't expect to be satisfied, she'd be less likely to have casual sex.
We've often believed that some young women's preference for slightly older men could have to do with status and resources on offer. Perhaps that's true. But perhaps the likelihood for greater pleasure from an experienced lover also plays a role. They always say it takes about 10,000 hours of practice, after all, to become an expert at something!
My advice based on these research findings: 
My advice based on these research findings:
1) Understand that for a woman, regardless of whether it's a man or another woman hitting on her, she's most likely to be interested in casual sex if she (probably subconsciously) thinks there is a very likely probability of having great amounts of pleasure from the encounter (e.g., an orgasm or more). Since it's comparatively hard for her to achieve this, she might be very choosy indeed!
2) Given that feeling relaxed and comfortable will likely also facilitate her chances of pleasure, when she does choose to have casual sex, it might well be with someone she already knows and trusts.
3) For anyone interested in having casual sex with a woman, practice your skills and your sensitivity to HER needs (I'll let your imagination figure out the rest). Figure out what works best to convey the message to her (a topic I'll post on in the future) -- that YOU are just what she needs to help her reach her sexual ecstasy!!
Sources:
(2) Abramson, P. R., & Pinkerton, S. D. (2002). With pleasure: Thoughts on the nature of human sexuality. New York, NY: Oxford University Press.
(3) Armstrong, E. A., England, P., & Fogarty, A. C. K. (2010). Sexual practices, learning, and love: Accounting for women's orgasm and sexual enjoyment in college hookups and relationships. Manuscript under review.
Copyright © 2012 Bjarne M. Holmes. All rights reserved.
About the author: Dr. Bjarne Holmes is Associate Professor and the Program Director for Psychology at Champlain College in beautiful Burlington, Vermont. His research focuses on attachment, well-being, health, relationship attitudes and beliefs, and the role of media influence on social identity in young adults. Dr. Holmes is an Associate Editor of the Journal of Social and Personal Relationships and he produces the journal's podcast series,"Relationship Matters" (download the podcasts for free here). He's also a regular contributor to the web page Science of Relationships (read his articles here). Dr. Holmes is available for media interviews, expert commentary, or consulting.
