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Two researchers wanted to know what happens when a manager needs an employee to handle work that wasn't theirs to begin with. Maybe a colleague is out sick, or an angry client needs extra care, and the team needs backup.
One of 63 managers who took part in a recent Organization Science study simply needed one of her finance employees to take notes at her team's most important weekly meeting. She knew two people who could do it well and "don't appear to mind." One in particular had a reputation for helping out. "I tend to select him," she said, "if no one else seems interested."
The formal research that followed was far larger. Lead researchers Sangah Bae of Northeastern University and Kaitlin Woolley of Cornell drew on 10 separate experiments with more than 4,300 managers and employees and found that managers tend to reach for whichever employee seems to enjoy their job most, again and again, until they're carrying far more than a fair share of the work nobody else wanted.
It's exactly the habit that's pushing the best people toward the exit.
Why managers keep making the same mistake
Ask an employee who loves their main job to take on something unrelated and tedious, and their enjoyment doesn't survive the switch. In the research data, the more enthusiastic employee's satisfaction with their main work sat at 5.19 out of 7. Handed the extra task instead, the employee saw their sense of enjoyment fall to 2.49. A coworker who cared less about the job experienced a far smaller dip, from 2.08 down to 1.24.
Managers thought the employees' passion for the job would protect them from burnout. They were wrong. The enthusiastic employee reported a burnout score of 4.86 out of 7 from the added work, while their less invested coworker reported 4.93. With the two numbers essentially tied, the finding proves that enthusiasm alone can't soften the burden of any additional workload.
Researchers call the underlying error "motive oversimplification," the habit of taking one true thing about a person and treating it as an explanation for everything else about them. A manager facing unplanned work typically narrows the choice down to two or three people and decides on the spot, without checking whether that same person already got the last few extra assignments. Most managers say they face this exact choice at least once a month. Nothing forces the pattern into view.
Left alone, the habit doesn't fade. Researchers followed real managers making this same choice every day for a full working week. Even on their most balanced day, they still gave the extra work to the enthusiastic employee 61 times out of 100.
The real price of an uneven workload
That persistence carries a real cost, and it lands on exactly the wrong person. Give the enthusiastic employee an uneven share of the extra work, and their odds of looking for a new job jump by close to 40%. Give a less invested employee that same uneven share, and almost nothing changes for them. A company loses nothing by splitting the work evenly. Keeping it uneven costs the company exactly the people it can't afford to lose.
Not even money can disrupt the pattern. In one experiment, a bonus depended on how well the enthusiastic employee did their main job, and they still missed it 69 times out of 100. Nothing about their actual work got worse. They were just spread too thin. Their manager had already reassigned their time to another, unrelated task, and that lost time was what cost them the bonus.
Reversing this behavior doesn't have to add overhead. Ask managers to assign several pieces of extra work all at once, instead of one at a time as each comes up, and they stop reaching for the same person nearly as often. Hand managers a short, plainly worded explanation that loving a job doesn't make someone immune to burnout, and they end up picking the enthusiastic employee no more often than a coin flip would.
Both interventions have to happen before the decision is made. After that point, there's no fixing what already happened to the person left holding the extra work.