I'm sure most of us have heard at least a variation of this myth. Unfortunately I failed to find the original source. Was there actually a study that claimed this?
A lot of the sites debunking this myth point to the book "The Social Organization of Sexuality: Sexual Practices in the United States" citing:
54% of men think about sex everyday, or several times a day,
43% think about sex a few times per month, or a few times per week
4% think about sex less than once a month.
These numbers show that almost half the men don't even think about sex once a day. But that book is from 1994 and from what I understand it was just a survey.
In 2006 Dr. Louann Brizendine published her book The Female Brain, in which see apparently claims:
Studies have shown that while a man will think about sex every 52 seconds, the subject tends to cross women's minds just once a day.
I don't have the book, so I don't know which studies she is referencing.
Are there actually studies (not just polls) that show men think about sex fairly often?