A recent study conducted by researchers in Tel Aviv and the Netherlands confirmed that nice women earn less than their assertive female counterparts. They interviewed a random group of 375 men and women at a Dutch electronics company and concluded that women who clearly express expectations and do not retreat from their demands are compensated better.

The researchers found that consistently, women invested more of themselves in their jobs than they were rewarded for, but the more dominant women faired better. They also found that women tend to rationalize their situation, making it less likely that they’ll make appropriate demands for equal pay.

Whether they were considered nice or assertive, all were still compensated less than the most agreeable man. The team hopes to replicate the study in the US.