Which is more effective in improving team performance: using positive feedback to let people know when they’re doing well, or offering constructive comments to help them when they’re off track?

New research suggests that this is a trick question. The answer, as one might intuitively expect, is that both are important. But the real question is—in what proportion?

The research, conducted by academic Emily Heaphy and consultant Marcial Losada*, examined the effectiveness of 60 strategic-business-unit leadership teams at a large information-processing company. “Effectiveness” was measured according to financial performance, customer satisfaction ratings, and 360-degree feedback ratings of the team members. The factor that made the greatest difference between the most and least successful teams, Heaphy and Losada found, was the ratio of positive comments (“I agree with that,” for instance, or “That’s a terrific idea”) to negative comments (“I don’t agree with you” “We shouldn’t even consider doing that”) that the participants made to one another. (Negative comments, we should point out, could go as far as sarcastic or disparaging remarks.) The average ratio for the highest-performing teams was 5.6 (that is, nearly six positive comments for every negative one). The medium-performance teams averaged 1.9 (almost twice as many positive comments than negative ones.) But the average for the low-performing teams, at 0.36 to 1, was almost three negative comments for every positive one.

So, while a little negative feedback apparently goes a long way, it is an essential part of the mix. Why is that? First, because of its ability to grab someone’s attention. Think of it as a whack on the side of the head. Second, certainly, negative feedback guards against complacency and groupthink.

And third, our own research shows, it helps leaders overcome serious weaknesses. The key word here is serious. Our firm provides 360-degree feedback to leaders. We have observed among the 50,000 or so leaders we have in our database that those who’ve received the most negative comments were the ones who, in absolute terms, improved the most. Specifically, our aggregate data show that three-fourths of those receiving the lowest leadership effectiveness scores who made an effort to improve, rose on average 33 percentile points in their rankings after a year. That is, they were able to move from the 23rd percentile (the middle of the worst) to the 56th percentile (or square in the middle of the pack).

A few colleagues have raised their eyebrows when we’ve noted this because we’re strongly in the camp that proposes that leaders work on their strengths. How do we reconcile these seemingly contrary perspectives? Simple: the people who get the most negative feedback have the most room to grow. It’s far harder for someone at the 90th percentile already to improve so much.

But clearly those benefits come with serious costs or the amount of negative feedback that leads to high performance would be higher. Negative feedback is important when we’re heading over a cliff to warn us that we’d really better stop doing something horrible or start doing something we’re not doing right away. But even the most well-intentioned criticism can rupture relationships and undermine self-confidence and initiative. It can change behavior, certainly, but it doesn’t cause people to put forth their best efforts.

Only positive feedback can motivate people to continue doing what they’re doing well, and do it with more vigor, determination, and creativity. Perhaps that’s why we have found with the vast majority of the leaders in our database, who have no outstanding weaknesses, that positive feedback is what motivates them to continue improvement. In fact, for those in our database who started above average already (but are still below the 80th percentile), positive feedback works like negative feedback did for the bottom group. Focusing on their strengths enabled 62% of this group to improve a full 24 percentage points (to move from the 55th to the 79th percentile). The absolute gains are not as great as they are for the most-at-risk leaders, since they started so much further ahead. But the benefits to the organization of making average leaders into good ones is far greater, because it puts them on the road to becoming the exceptional leaders that every organization desperately needs.

As an interesting aside, we find it noteworthy that Heaply and Losada’s research is echoed in an uncanny way by John Gottman’s analysis of wedded couples’ likelihood of getting divorced or remaining married Once again, the single biggest determinant is the ratio of positive to negative comments the partners make to one another. And the optimal ratio is amazingly similar—five positive comments for every negative one. (For those who ended up divorced, the ratio was 0.77 to 1—or something like three positive comments for every four negative ones.)

Clearly in work and life, both negative and positive feedback have their place and their time. If some inappropriate behavior needs to be stopped, or if someone is failing to do something they should be doing, that’s a good time for negative feedback. And certainly contrarian positions are useful in leadership team discussions, especially when it seems only one side of the argument has been heard. But the key even here is to keep the opposing viewpoint rational, objective, and calm—and above all not to engage in any personal attack (under the disingenuous guise of being “constructive”).

We submit that all leaders should be aware of the ratio of positive and negative comments made by their colleagues in leadership team meetings, and endeavor to move the proportion closer to the ideal of 5.6 to 1—by their own example.

*Authors’ Note: The journal that published this study has since expressed concern about the data. We first became aware of this research in Kim Cameron’s book, Positive Leadership. Like many others, we were distressed to learn of the incorrect data in the Heaphy and Losada research and we immediately ceased our citations upon learning that the study wasn’t correct. But we do believe the basic assumption and premise that leaders should provide more positive than negative feedback is correct.