When describing a joint effort, refer to colleague by name or by their title?
Written Texts

In the context of a written text I usually use the person's title letters (Mr. Dr. Etc.) and state their affiliation if it actually adds something to the point I'm trying to make. Say for example I wish to point out the collaborations I have set up with other institutions, then I'd probably be verbose about it. 

Of course it doesn't make sense to explicitly mention collaborators in all written texts. Neither it is customary to do so. For example in a paper the collaborators are listed as authors, and this collaboration relationship is therefore very explicit. In your thesis you should probably concentrate on your work. That doesn't necessary mean you shouldn't explicitly acknowledge collaborators, but that's the type of scenario in which I'd err on the verbose side.

Oral Presentations

In case you are referring to an oral presentation, you could state their title and position the first time you introduce them, and subsequently refer to them by their name whenever you mention them again. Something like:


  I conducted this work with Joe Rnano who is Distinguished Professor at the University of Academia.SE. Joe and I demonstrated that ...


I just came out of a conference and that's what most speakers did.