Your hairstyle says it all when it comes to impressing others about how smart you might be.
The “do,” in other words, reveals the IQ.

That’s the mane-breaking conclusion of "First Impressions and Hair Impressions", a Yale University study conducted by psychology professor Marianne LaFrance.

The Ivy League prof writes that when people begin forming a first impression about the type of person you are, it’s not your face that gives you away, it’s your hairstyle.

Jessica Simpson’s cascading blond locks may get you a hot date, but it won’t win you that Fortune 500 company job. The money’s on the bob-baring brunette to catch the boss’ eye at that interview.

According to LaFrance, a hairdo is all about perception and it has the power to say two things: high IQ or bimbo.

Tousled, short-haired women à la Katie Holmes or Halle Berry are viewed as more intelligent than Lindsay Lohan copycats, according to LaFrance’s study.

Also, women with long, straight, brunette or blond hairstyles, like Catherine Zeta-Jones, are perceived as the sexiest and most affluent, writes LaFrance.

“What people should think about is what kind of impression they want to make and is my hairstyle helping or hindering that operation,” says Jodi R. R. Smith, an etiquette consultant and founder of Mannersmith in Salem. “If you’re a laid-back, easygoing kind of gal, a wild hairdo is great. Use your hair appropriately.”

Men also have to pay attention the next time they head to the barbershop. Those who emulate stars like Matt Damon and Brad Pitt are seen as the most confident and sexy. The short, well-kept cut, with a front flip, landed both of these actors the moniker of People’s “Sexiest Man Alive.”

Men who opt for a traditional cut over a buzz cut are viewed as the most intelligent and affluent. The medium-length, side-parted do is a favorite of presidential candidates Mitt Romney and John Edwards.

For those who believed Fabio’s lion’s mane would court a flock of ladies — think again. Long, flowing locks on men were said to make others think they are no brains and all brawn.