Professor Phelps from an Australian university once ran a revealing social experiment.
For a month, he divided students into teams of four and gave them 45 minutes to solve real-world business and management challenges. The
top-performing team received a $100 reward.
What the students didn’t know was that some teams secretly included “planted participants” assigned to play specific roles:
The Disengaged One — leaned back, scrolled through their phone, barely participated, and ignored the group.
The Sarcastic One — dropped cutting comments during discussions like, “Seriously?” or “Have you ever actually led anyone before?”
The Pessimist — looked defeated from the start and constantly doubted the team could solve the problem or succeed at all.
Professor Phelps discovered something striking:
Even when the other three team members were highly capable and motivated, the presence of just one destructive person reduced overall team performance by 30–40%.
In other words, team effectiveness often depends less on how many strong performers you have — and more on whether there’s even one person who drags the group down.
Key takeaway
The job of leaders and HR managers isn’t only to support top performers. It’s also to address or remove behaviors that undermine team culture and collaboration. Strong teams can thrive on their own — as long as no one is quietly poisoning the environment.