You’re faced with a difficult decision, and suddenly you feel the right answer in your gut.

That’s intuition, and it’s not to be ignored, insists anthropologist and human attraction expert Dr. Helen Fisher.

“While intuition may seem to arise from some mysterious inner source, it’s actually a form of unconscious reasoning,” she explains. “It’s rooted in the way our brains collect and store information. As you accumulate knowledge—whether it’s about what books your spouse likes or how to play chess—you begin to recognize patterns.”

Here’s why:

1. Your brain unconsciously organizes these patterns into blocks of information, a process the late social scientist Herbert Simon, PhD, called “chunking.”

2. Over time, your brain chunks and links more and more patterns, then stores these clusters of knowledge in your long-term memory. When you see a tiny detail of a familiar design, you instantly recognize the larger composition—and that’s what we regard as a flash of intuition.

3. This elaborate brain circuitry likely evolved so that our forebears could quickly size up a person or a situation. Our female ancestors, in particular, needed this skill: They had to tune in to their infants to enable them to survive. And this helps explain why women today have an edge when it comes to reading people.

So listen to your gut feelings instead of brushing them aside.

“Your intuition may not always steer you right, but it can be a useful first step in decision-making,” adds Fisher, who offers insight into when to trust your intuition — and when to let your head take the lead.

Use your intuition when:

• You are doing something you’re experienced in. “Intuition is really learned expertise in disguise,” she explains. “So if you’ve played tennis your whole life, go with your instinct on the court instead of thinking through each stroke.”

• You are considering getting a second opinion. Fisher refers to Judith Orloff, MD, a psychiatrist at UCLA and author of “Second Sight,” who says: “Listening to your body’s signals can help prevent bigger health problems. If your doctor dismisses a nagging symptom as “nothing serious” but you’re still convinced there’s something wrong—go with your hunch.”

• You are shopping for a home. “Don’t just endlessly analyze the financials; listen to your gut,” Fisher notes. “Studies have found that purchasers are more satisfied with a big-budget item when the decision is made incorporating unconscious thought rather than by conscious deliberation alone.”

Let your head decide when:

• You are sniffing out a lie. Fisher points to David Myers, PhD, author of “Intuition: Its Powers and Perils,” who says: “There are no easily detectable signs that indicate lying, so even if you’re adept at reading people, you can’t infer dishonesty based on the other person’s gestures or behavior.”

• You are hiring someone for a job. If there’s a contest between your positive gut feeling and what work samples and recommendations tell you, forget your gut. Myers adds: “Your intuition may be based on something superficial—like whether the candidate reminds you of a close friend—that has nothing to do with performance.”

About Helen Fisher

Helen Fisher, PhD, is a biological anthropologist, research professor, and member of the Center for Human Evolution Studies in the Department of Anthropology at Rutgers University. She is also the Chief Scientific Advisor to the Internet dating site, Chemistry.com, a division of Match.com. She has conducted extensive research and written five books on the evolution and future of human sex, love, marriage, gender differences in the brain, and how your personality type shapes who you are and whom you love.

For more information about the author and her books, visit: www.helenfisher.com.

View Dr. Fisher’s presentation at the World Future Society’s 2007 Conference, where she discussed the topic: Drugs or Love?

The photo (at top) is of Dr. Fisher presenting at the 2008 TED conference in Long Beach, CA.