What impresses a new boss more: attitude or ability? If your answer is ability, think again. Attitude—especially a negative one—might be the determining factor in your relationship with a new employer.

"We found that supervisors were able to pick up on negative traits such as , hostility, or instability early in the relationship," reports David V. Day, Ph.D., assistant professor of psychology at Penn State. "These traits can destroy a good working relationship almost before it begins."

Even if a new employee has considerable ability, a negative attitude is what may stick in the employers mind. And once that is formed, it's hard to change. "Negative traits make a more powerful and long-lasting impression than positive ones," notes Day. "And even the most employees are unlikely to join the supervisor's inner circle it they are perceived as angry, irritable, or ."

In his study, co-authored with Elona C. Crain, of Tulane University, undergraduate student "leaders" had to pick who they wanted to work with in an exercise. Their choices were based both on results from a mental-ability test and a questionnaire measuring positive and negative feelings and emotions. The results: the leaders favored good vibes over big brains.

Can you suppress negative feelings and fool the boss? Attitudes, especially negative ones, are often revealed through facial expressions and .

Day found that these hard-and-fast first impressions are part of an effort by the boss to find his own group within the employee pool. The "in" group gets choice assignments and more flexibility in how they work; the "outs" are saddled with more structure and drudge-work. This herding happens quickly—forget about the three-month probationary period—and it's hard to change once you've been branded.