Table 5 Evidence and interpretation of personal proximity as a mediator of social proximity and temporary geographical proximity

Personal proximity mediating the effect of social proximity on collaborations

“Knowing the person personally well plays an important role, although not always. Professional relationships, people you meet in conferences continually and you discover that you have common interests, expertise that are complementary so that you can do more together than you could do separately and then one thing leads to another. Then you start doing collaborative research. It has never occurred to me: “Hey, I have an idea and I need a chemist, I have got to go and find a chemist!” That has never happened to me. […] Maybe it is interaction with the people which stimulates me to think of collaborative projects and then I know immediately who the person is going to be.” (Interviewee TUD3A-4)

Interpretation: Social proximity allows one to familiarize with potential collaborators

“Yes, [Collaborator’s name] has joined the team at [Name of a university spin-off firm] as a researcher when I was still part-time project leader at the place. I know him well on the personal level. We were on the same hockey team for five years or so.” (Interviewee TUD1A-1)

Interpretation: Social proximity (working at the same spin-off firm and sharing membership of a hockey team) feeds personal closeness, which in turn led the interviewee to select him as a collaborator later on from an array of cognitively close potential collaborators

“There is another one, [Collaborator’s name], from [Large high-technology firm’s name]. […] He works in [Large high-technology firm’s name] and I also worked there, so I know him very well.” (Interviewee UT2A-3)

Interpretation: Professionals association in the past—sharing a previous employer—enabled the collaborators to develop a close personal relationship

Personal proximity mediating the effect of temporary geographical proximity on collaborations

“What is needed is that you have the opportunity to meet and have some dinner or so together. I like to do that. Very often, if I meet them, I like to have dinner with them. Not with 10 people, but with 2 or 3, and then we talk. That’s what I like. Or lunch, or that kind of thing. But you can also sit in the train for a few hours.” (Interviewee TUE1A-3)

Interpretation: Temporary geographic proximity as a way to assess personal fit with potential collaborators

“Because of a [Funding organization’s name] grant through which I visited the Institute of [Specialization] in [City X] and I saw him as an eager guy who wanted to move ahead. That was one observation. […] I had told this person [colleague] when he still worked in (City Y) that we needed for our project [specialization] engineers and I told him that if you really want (specialization) engineers, we should go to (City X), because in The Netherlands they are no longer trained at a sufficiently high level. And that’s how (collaborator’s name) came to (City Y).” (Interviewee TUD2A-3)

Interpretation: A visit abroad created temporary geographical proximity that enabled the interviewee to judge the personality of this potential collaborator

“I was there a couple of times from a consultancy perspective really, twice to be precise, and we extended our collaborative relationship when they also came to visit here. One thing led to the other…” (Interviewee TUE2B-1)

Interpretation: Brief visits serve as a prelude to more significant collaborations