Gender? It's A Gray Area.

You buying this? There is some disagreement. The 53-year-old neuropsychiatrist, by way of Yale and Harvard, with the Tina Fey eyeglasses and her auburn hair back in a ponytail, has been offering her take on the female brain on the morning talk show circuit and is scheduled for an upcoming episode on ABC's "20/20." Her book cracked the Top 10 list at Amazon and is garnering generally favorable reviews -- and heat from her critics, who say Brizendine (pronounced BRIZ-en-dine) is guilty of hyping gender differences and misrepresenting the research.

In the pages of "The Female Brain," briskly selling as an owner's manual for women and a kind of cheat sheet for men, Brizendine promises to reveal the neurological explanations why:

· Men think about sex every 52 seconds, while a woman does only once a day.

· Women speak faster on average -- 250 words per minute vs. 125 for a typical male.

· A woman uses 20,000 words per day, while a man uses only 7,000.

· Boys don't listen to mommy (answer: because "he physically cannot hear the same tone of warning").

· And "a woman knows what people are feeling, while a man can't spot an emotion unless somebody cries or threatens bodily harm."

These are simply remarkable differences, and naturally they have been repeatedly cited in book reviews and news reports about "The Female Brain" and its claims.

She is a motor-mouthed empath with bat-like hearing? Or does it just seem that way, because men think about sex 69.2 times an hour?

Alas, we do not know if any of these factoids are true -- and they very well may not be.

Brizendine includes 58 pages of references and 19 pages of footnotes in her book, but when asked to produce the primary scientific studies that produced the numbers above, she could not.

"I have to say the pattern is very consistent. When you attempt to track down her sources for some of the more sensational claims, it is not satisfactory," says Mark Liberman, a professor of linguistics and computer science at the University of Pennsylvania who has blogged on the language-use claims in Brizendine's book.