"That was exactly not what we're saying," O'Neill said. "Nobody is saying act like a lady. The point is to learn to assess the situation and act accordingly."
Janet Hanson, a former Goldman Sachs executive, said assertiveness was a very important trait in her finance career, but equally important were an awareness of company culture, common sense, and confidence.
Hanson, who first joined Goldman Sachs in 1977, was the first woman to be promoted to sales management there. She said aggressiveness was crucial when she worked on the trading floor, or what she called "the Wild West."
"You have to have a tougher exterior. There's a lot of money on the line and trades happen very fast. If you can't survive in that culture, whether you're male or female, you're out," said Hanson, who started a network for female professionals and students called 85 Broads. Named after Goldman Sach's former New York City address, 85 Broad Street, the organization now has 25,000 members.
But what worked in the sales and trading group at Goldman Sachs would not necessarily work in every circumstance, said Hanson -- for instance, in the boardroom, with the investment banking division, or in diplomatic conversations with clients.
"You also have to know how to discuss the market with your clients without any four letter words," said Hanson. "The key is to understand your work environment."
Hanson said she was able to earn the respect of her peers because she extensively studied the firm's history even before her first day.
O'Neill agreed that leadership coaches and successful executives are already aware of the importance of self-monitoring.
"People have been probably doing this all along, but not in such simple terms. There's no blanket rule for how to behave. It's not better to be aggressive all the time, or be kind all the time."
But can people learn how to monitor their behavior like assertiveness and dominance?
Yes, said O'Neill.
"There is some evidence people are genetically born with some traits. Only 25 percent of variance in behavior is related to genetic factors, which is not trivial," said O'Neill. "But the rest is learned, absolutely."
Hanson said she hopes other women do not attempt to emulate men to be successful in the workplace.
"Being able to tell dirty jokes or talk about your escapades at a bar, that doesn't garner you respect, ever," said Hanson.
O'Neill's advice to women who want to be successful in the workplace is: don't disguise your true self, but learn to read situations.
"There's a great demand for women leadership," said O'Neill. "Women may have certain traits that may predispose them to be great leaders. Part of their socialization is to be attentive and aware and advocates of others. In combination with assertiveness and aggressiveness, it's a dynamic combination."
O'Neill said aggressiveness is not a trait women should hide.
"The trick is learning when to use it," she said.