The question is, why do many people join electronic discussion lists but then do not contribute (write) messages; and does learning depend upon contributing or in fact do lurkers learn as much as overt contributors.
Three major points that bear on this:
The NetSem experience: an email seminar course that performed much better than the face to face format it replaced, but which depended on the interaction skills of the facilitator including direct incentives for every contribution.
A quite advanced development in this direction is Finbar Dineen's work.
The learning value applies separately to reading and to generating a contribution, although individuals may not be aware of the added value of saying something. All goals have not only an importance (value if achieved) but also an urgency. Lurking is often the behaviour of those with a real interest, but whose job demands that other things get priority. By "social dynamics" I want to refer to the demands of managing any interaction. Thus if there are a thousand subscribers to a list, only a few can contribute actively; and contributions must not only be manageably few but timely.
It seems likely that learners can learn by being an audience to others' interactions, although this has not yet been proved. It also seems likely that the benefits may not be of the same kind as in other kinds of learning. For instance, learning how other learners are doing on this topic, learning what counts as a question, learning what status an "answer" has (e.g. universally accepted fact, a leading opinion, one of several contending theories each with problems, the teacher's pet belief, ....), learning what this subject is about and what is (and isn't) known, learning about some topic you would never have sought out because you didn't know it existed or was interesting. The obvious pre/post tests and exams of a pre-determined content cannot detect any of these kinds of learning.
I don't have a full paper on LBO yet, but here are 3 chunks: 1, 2, 3.
[B] Three factors determine lurking behaviour?
My personal summary of the issue: where point [B] above came from
The whole ITFORUM discussion on lurking that led to this notion.
[C] LBO (Learning by Onlooking)
A brief note on LBO (learning by onlooking)
Another brief note on LBO
Yet another brief note on LBO