Insecure coworkers can create an uncomfortable work environment, and their behavior can range from unproductive to mean. Insecurity is common in almost everyone, but the level of insecurity and how much it affects behavior can also vary greatly.
A pattern of behavior that includes arrogance, bullying, bragging and aggression can be a mask for someone overcompensating for her insecurities. In fact, people who engage in this behavior are often covering up something. For example, if the person boasts about all of her accomplishments and has to tell everyone about it, she's likely insecure.
Employees who are constantly looking to please and receive praise likely have an insecurity issue. Wanting to receive praise is fine, but others need external validation to feel worthy. This is in part linked to low self-worth. Seeking out compliments, going far beyond what is expected and being a "yes man" can all be signs of insecurity. In the corporate world there may also be other reasons for these behaviors, such as trying to get ahead. However, those sucking up simply for career advancement are likely not as needy.
One way some insecure people make themselves feel better is by putting others down, by mocking others' achievements and diminishing them. A secure person is happy to see others around them succeed. Negative or anti-social behavior not in alignment with team building and company growth can be a sign of insecurity. Overly competitive people may also be insecure, having to prove their worth by beating someone else.
Shyness, social withdrawal, fidgeting, anxiety and avoidance are all typical signs of insecurity. Insecure people are less likely to be social in the office and not want to speak out or contribute much to the team. They may be overly anxious, nervous and even fidget when placed in uncomfortable situations. The insecure person may avoid situations that require confidence; such as giving presentations.