Q:

Hand out lecture notes or not? 

It lectured a stochastics course for pre-service teachers last semester and had a teXed manuscript for myself which grew as the course was running.  After some debate with the students, I made a version accessible online.  In university courses, my students are free to attend the lessons or not.  I think some thought then they would not have to come at all, some stopped copying from the blackboard, some struggled with my typos.  That's the bad side of the coin.  On the other side, students could check the lecture when they had not been there (some of them had another course overlapping), they now could think when I wrote and copying from the blackboard may generate new typos. 
Question: Is there any founded discussion (mabye research) on the effects of handing-out lecture notes? 
I know some lecturers do hand-out notes, some not, some hand-out notes with gaps to be filled in the lecturer.  However, their reasons mainly lie in personal experience but not scientific debate. 

A:

I hand out notes in most of my courses.  These notes parallel my lectures, sometimes precisely, sometimes just roughly.  Some of them are typed, some of them are pdf-scans of my handwritten work.  I usually post a day-by-day lecture schedule detailing where I'll be in the notes as best as I can forecast.  I suppose, in principle, there is a possibility that students think:

I can skip class because: he posted notes and I already have the inside scoop beyond the text.. 
I can just write nothing in class because: I already have these notes and printing them out makes the material stick in my mind just as much as actively writing them...

I suppose both of these are possible, but, I actively discourage both practices at the outset by:

including more than is required in my lecture notes: if they come to class they get a better sense of which parts of the notes are beyond the required core of material. 
adding examples not in my posted notes: this works best in the lower level classes where it is safe to make up examples, obviously this requires additional work in higher courses.  In any event, taking notes in my course adds to my posted notes. 

Both items above go to the point that I don't just read my notes.  Rather, my notes are an indication of the totality of my thoughts on a topic, sometimes, there is just too much for lecture.  My notes go into second or third order caveats whereas the lecture is more towards emphasizing the first order material.  As a somewhat extreme example, I prove the n-th order variational parameters formulae via some tensor arithmetic.  That is something I would not want to lecture in differential equations as it has little to do with my expectations for them in the course.  On the other hand, if I can peak the interest of just one of them to the joys of tensor calculus then it's a win in my book. 
Warning: they will complain.  Some students are simply annoyed if you do anything but teach them how to do the calculations you will put on the test.  I frankly don't care.  I refuse to cater to this student as they endanger the whole concept of university.  On the other hand, the students who are genuine in their curiosity typically appreciate the effort of the notes.  It is for those students I post them.  On the whole I still have students attend and take notes so in my opinion the hypothetical that it shuts down both activities is not observable in my situation. 

A:

@AndrasBatkai's answer surprised me a little, and I don't disagree with it.  But/and contemplating the plausible factoids of his remarks makes me a little unhappy, perhaps only "unhappy with reality":
Yes, certainly, after he pointed this out, I can agree that making PDFs (or whatever format) available ahead of time, or promised, does lead a significant fraction of the student population to disengage.  Not to take advantage of the further possibilities, such as making notes on printed-out notes, or doing the tablet version of this, but, ... just disengaging, or not going to class at all, and not really looking the notes, either. 
But this reminds me of a different wording for the question... in effect, to what extent are we (educators, mentors) responsible for preventing self-sabotage by students? 
The real problem arises when a practice that hugely benefits 75% of the population has a bad resonance with the other 25%.  Then what? 
That is, making my notes available is mostly beneficial, but seems to fatally confuse a small but non-trivial fraction of the population.  Dang.  But is this the real "final exam" for them?  Or is it just a misunderstanding?  At this point, I still don't really know, although I do know that predisposition to fall into this trap is not a survival trait. 

A:

Writing is an essential part for most of us when learning mathematics.  I think it is essential to get the students to learn how to take notes and, in an ideal world, after each class to write out in every detail the content of that lecture.  We should do everything to encourage students to take notes and write more.  
Some even think that handwriting is essential and we should encourage it in contrast to taking notes. 
Because of this, if possible, I try not to distribute my notes or my slides.  This may also be a serious problem for those who cannot attend the lecture.  I feel bad about this.  I try, however, to make a balance between taking notes and discussing, developing the material together.  
If I worked out some parts of the material and I feel it is better than the textbook, I usually put that part when we finished the lecture on my homepage. 
ADDED: I just came across this article which also discusses the advantages of handwritten note-taking (though in a different context).