The causality argument here would likely need to be investigated. How did these teams end up structured this way? Was it because their members were empathic, or did they rigidly choose to take this approach as they knew it would work?
I'm assuming the good teams arose from many members with strong social skills -- but that's just an assumption.
The details are in the study. But I believe standard hiring practices were used, primarily based on technical merit and critical thinking. (You know, those weird Google interview questions.) The point of the study was to try to determine what made some Google teams successful and others not. And in fact they could not find any commonality among successful teams at first. They initially examined things like age, diversity, education, skill level, etc. and came up with no correlations. That's when they started trying to find other factors and discovered the connection between success and the "emotional intelligence" of the team.
You didn't say this, but I wanted to point out. I do not think you have to be extroverted to have emotional intelligence. I am introverted and tend to have some. Rather I think emotional intelligence means really listening to and processing what other teammates are saying. It is all too easy to rely on our old mental models of people and situations and ignore new (especially contrary) information. It is pretty noticeable when someone on the team chronically "doesn't listen" or "does their own thing". That can lead others on the team to decide they no longer have to put in the effort to listen either. This video is pretty relevant to that aspect. She is describing the results of a different study, and you can back up to get the overview of that study. And in fact, I'm pretty sure I heard of Project Aristotle from another Sandi Metz video. Both links should be at the relevant section of the video.
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