What’s the Secret Ingredient to Great Mentorship?

Until recently, nothing conclusive. Some scholars even suggested that mentorship had troublesome side effects, including favoritism and “cloning,” mentors’ tendency to push protégés toward career paths exactly like their own.

But new research from Brian Uzzi, a professor of management and organizations at the Kellogg School, shows that mentorship is indeed beneficial—especially when mentors pass down unwritten, intuitive forms of knowledge. The study, which analyzes the careers of more than 37,000 scientist mentors and protégés, suggests that mentors who pass on tacit knowledge gained through their work experience rather than codified skills produce mentees who are significantly more likely to become superstars of their fields.

What’s more, “mini-mes” don’t necessarily thrive. Protégés are most successful when they work on different topics than their mentors.

For many of us, that’s a new way of thinking about mentorship. “People almost always think of the mentor as the really active element. The mentee is the passive element, absorbing the mentor’s knowledge,” Uzzi says. “Some of that’s true, but it turns out it’s really not a one-way arrow. It’s incumbent upon the mentee to branch out, take their mentor’s tacit knowledge, and do something that breaks new ground. The mentee has a big responsibility for their own success.”

Yet strong mentorship has been facing a serious threat: COVID-19. Since the tacit knowledge that makes mentors valuable is best imparted face-to-face, Uzzi worries that the loss of in-person communication during remote work may hurt mentees’ career prospects.

Quantifying the Value of a Mentor

Uzzi and his collaborators—Yifang Ma of Southern University of Science and Technology, China, and Satyam Mukherjee of the Indian Institute of Management Udaipur, both former post-doctoral fellows at Kellogg—were able to conduct the study thanks to a new digital tool. In the last decade, scientists have created massive databases of their fields’ intellectual “family trees,” tracking which scholars advised which students.

Uzzi, Ma, and Mukherjee pulled data from these family trees and linked them to other relevant information, such as job placements, grants and awards, and publications. Their data set ultimately included 37,157 scientists and mentees and the 1,167,518 papers they produced between 1960 and 2017.

But the researchers had a major hurdle to overcome. Mentees aren’t randomly assigned to mentors, so it’s hard to know whether their successes or failures can be attributed to mentorship or other factors. “The mentors who generally have the best records and the best reputation tend to attract students who have the most talent coming into the program to begin with,” Uzzi says.

This phenomenon, called assortativity, had thwarted previous studies of mentorship. Fortunately, their massive data set allowed Uzzi and his coauthors to undertake analyses that weren’t possible before.

First, they identified six groupings of mentors who looked “exactly like each other on paper,” Uzzi says: they taught in the same fields at equally prestigious institutions, advised the same number of students each year, published the same amount, and were cited the same amount. As expected, these statistically identical mentors attracted students of similar talent, as measured by their first job placements, lab sizes, and IQs (obtained from Mensa International).

With the assortativity problem accounted for, Uzzi says, “we still had one other problem, which was, how are we going to see if mentors pass on valuable information to their mentees or not?”

A “Hidden” Skill That Sets Good Mentors Apart

The researchers wanted to understand what mentors were or weren’t passing along to their mentees. So they came up with an idea: They had already identified groupings of identical mentors. What if, within each grouping, they could identify one mentor with a special, hidden trait and see whether or not they passed it to their students?

Eventually, they hit on the perfect “hidden” skill to study: the ability to produce research that goes on to win scientific prizes. Prize-winning papers “tend to go after really particular and important problems and answer them in not just competent but stylish ways,” Uzzi explains.

Of course, once a scholar has won a major scientific prize, they will attract stronger students. So the researchers confined their analysis to the years before researchers received their prizes.

They focused their statistical analysis on “groups of essentially indistinguishable mentors attracting students of the same quality, except one mentor in each of these groups has a hidden quality: they’re going to be a future prizewinner,” Uzzi says. That meant they could compare how the students of future prizewinners and non-prizewinning mentors fared.

The Best Mentors Pass Along “Special Sauce”

When the researchers analyzed the performance of protégés of future prizewinners and non-prizewinners, the differences were striking: students who studied under a future prizewinner were almost six times more likely to become superstars in their field than equally talented students of non-prizewinners. (The researchers defined “superstars” as scientists who had won major prizes, were members of the National Academy of Sciences, and were among the top 25 percent most-cited scholars in their field.) Clearly, prizewinning mentors did indeed pass along what Uzzi calls the “special sauce” to their students.

But as they went deeper into their statistical analysis, the researchers found other intriguing patterns. To their surprise, the differences between the students of future prizewinners and non-prizewinners didn’t emerge right away. In fact, in the first ten years of their careers, the students of non-prizewinners published more papers, were cited more, and had more coauthors than the students of future prizewinners. But in the second decade of their careers, the students of future prizewinners begin to outflank them.

Uzzi has a theory as to why. “In science, it’s generally easier to publish solid work that isn’t controversial in any way,” he says. “It takes time for the best ideas to mature and for scientists to begin to see the real value of work that is more controversial. That may explain why the students of the future prizewinners eventually overtake the students of the non-prizewinning mentors.”

Another surprise: the most successful protégés of all are those who study under future prizewinners but ultimately go on to work in different subject areas.

In some ways, this goes against conventional wisdom: students who are successful and carry on their mentors’ work are often perceived as rising stars. But in the long run, the most successful scientists are those who chart their own paths.

“When a student gets this ‘special sauce’ and they apply it to being a mini-me of their mentor, they still do well. But if they apply it to an original new topic of their own, they do even better,” Uzzi says. “You want the special sauce, but if you also apply it to something new, the special sauce is even more valuable to you.”

Great Mentors Offer More than Just Expertise

So, what exactly goes into the special sauce? The current research doesn’t provide a full recipe, but offers a few hints. First, it’s clear that the best mentors pass on something that goes far beyond subject-matter expertise. (If that were the case, mini-me mentees would have been the most likely to succeed.)

Uzzi and his coauthors believe that what’s being passed between future prizewinners and protégés is tacit knowledge. Mentees aren’t just learning concrete skills from their mentors. They’re also picking up how their mentors come up with research questions, how they brainstorm, how they interact with collaborators, and so on—knowledge that is difficult to codify and often learned by doing.

That’s especially important to consider in the age of COVID-19, when more and more of our interactions take place through screens, and some have begun to question whether remote mentorship can replace the in-person variety.

“As far as we know, the fullest transfer of tacit knowledge is conveyed in person,” Uzzi says. “What this research says to me is that you really want to respect the value of face-to-face interaction.”