The structure of the experiment seems to have been just a correlation between collaborative hours and some measure of happiness. I wonder if the causation doesn't run the other way to what they propose though. When I'm happy in work, I don't really feel the need to have to work to grow my network outside my team. I have worked a job though where things just weren't clicking, so I did put more effort into trying to make them click by meeting people. That would have included getting involved in more projects, and doing a bit more collaborative work.