People overstate their contributions to group projects not just due to egocentrism but also because credit is hard to estimate in large groups, a new UC Berkeley study shows. Estimates from students asked to quantify their contributions to a group project consistently totaled as much as 140%.

If you’ve ever worked in a team, chances are you’ve probably given yourself more credit than you’re actually due. A new study from UC Berkeley’s Haas School of Business shows that people overstate their contributions people in part because we’re naturally egocentric and also because it gets harder to consider everyone’s contributions when groups are larger.
In the first of four experiments, the study participants–699 MBA students enrolled in a negotiations course–answered six questions about how much work, percentage-wise, they contributed to a team project. Their totals consistently added up to more than 100%. All together, the responses from individuals within teams of eight or more totaled more than 140%.
Managers who are skeptical about an individual employee’s contributions should first ask that person to report what their teammates did before listing off their own contributions. The researchers claim this tactic helps draw out the truth from credit hogs.