Men Think about Sex More than Women
In The Female Brain by Louann Brizendine she claims that men think about sex every 52 seconds. This means in a given day they would think about sex every 86000/52 = 1,662 times a day. She says in comparison, women only talk about sex once a day.
She quotes four studies to prove this. However, Mark Liberman tracked down all four studies - and none of the studies said anything about men or women thinking about sex -
The Four Studies about Men and Women Thinking about Sex
In comparison, Mark *was* able to find a study that talked explicitly about men and women thinking about sex -
"Data comparing the frequency of internally generated thoughts (fantasies) and externally prompted thoughts (sexual urges) among young heterosexual men and women indicate that men report a greater frequency of urges than do women (4.5/day vs. 2.0/day), although the frequency of fantasies were similar (2.5/day; Jones & Barlow, 1990)."
So we fantasize equally. However, we are aroused by 'external things' slightly less frequently.
I think that's because guys are willing to go after most any female - while us females are a bit more discriminating about who we want to chase ;)
Now that being said, studies do show that men in general want more sex than women. That women are very eager up until they get married - and then their desire tends to taper off.
WebMD Article on Sexual Desire
"About one in five women report that their husbands have turned them down for sex, Driscoll says, while half of all men say their wives have turned them down."
So still, it's not 90% and 10%. I know many women who fall into that 20%.
Another problem of course is that women sometimes want romance and attention before whoopie - so when the studies say "wives turned them down" what it really means "the guys wanted a quickie and didn't take the time".
Forum Discussion on Men vs Women Talking
The Female Brain - Louann Brizendine
Lisa's Biology Pages