When Nicki Crick began studying the psychology of adolescent girls, people still used the rhyme "Sugar and spice and everything nice." It didn't take her long to shred the stereotype and expose a very different reality.

In groundbreaking research as a professor at the University of Minnesota, Crick showed that girls and women often employ a "relational" form of aggression that can be just as disturbing as the physical aggression that boys and men sometimes use to get what they want.

Crick, who ultimately became director of the university's respected Institute of Child Development, died Sunday after a brief bout with cancer. She was 54.

Crick's research became widely known among academics in the mid-1990s, then won wide public recognition in 2002, when the New York Times cited her work in a magazine story titled "Girls Just Want to Be Mean." Shortly after that, the Discovery Channel broadcast a documentary titled "Rituals of the Girl Tribe," featuring Crick and her findings.

Girls and women, Crick found, are experts in refining the art of social exclusion to hurt one another. They sometimes utter mean gossip as a weapon, for example, and threaten to end friendships or destroy romantic relationships in order to control and punish others.

In 2001, Crick was recruited to Minnesota from the University of Illinois.

"Nicki's research unpacked the whole beast," said Megan Gunnar, a regents professor at the U and now director of the Institute of Child Development. "There was a lot of work being done on why kids are hyper and aggressive, but Nicki did a lot of additional research that made us think about emotions -- that there was a whole other world out there with this covert aggression amongst girls. To be a victim of that can be brutal for kids."

Gunnar said Crick found that girls with such aggressive traits often had mothers who had used the same forms of aggression on them. "The most vicious have a lot of other serious emotions that have gone unmasked," Gunnar said.

Crick's legacy survives narionwide in classrooms, where school-based programs seek to reduce aggression among girls by teaching them better, peaceful ways to resolve conflicts that could otherwise become emotionally and physically devastating.

Crick, who was divorced, had no children and lived in Woodbury with what she called her "wolf-pack" -- three much-loved huskies.

Her office at the university was known among colleagues as a reliable pit stop for anyone in need of a quick candy fix. During Halloween, it was common to see her in costume, handing out goodies to anyone passing by, Gunnar said.

"She has changed the field," Gunnar said. "You don't study aggression without studying relational, covert aggression and gender."

A memorial service will be held from 1 to 3 p.m. Saturday at the Wulff Funeral Home in Woodbury. The university will conduct a memorial service at 10 a.m. on Dec. 1 at the McNamara Alumni Center.

Paul McEnroe • 612-673-1745