What is "shadowing" for speaking practice? Does it work?

I often used "shadowing" my own Chinese study - repeating as I listened to tapes or movies - even before I knew the name shadowing. Basically, it just makes sense because the more you practice a language, the easier it gets. We probably don't need fancy theories to agree that it is an effective way to practice.

Below is one 2007 paper paper on the subject. I attended a workshop in 2006 by John Wiltshier of Miyaki U. once and this paper is basically the content that was presented.
http://www.efcafe.com/fluency_through_shadowing.pdf

Here are some of the main points:

-Research (which I have not examined personally yet) seems to show that "shadowing" or repeating (mentally or orally) input immediately after hearing it improves listening comprehension, oral reading fluency, and speaking in terms of prosodic elements (rhythm/pausing/intonation). It is probably more effective than "just listening" because "attending" to the input by saying it puts in the processing mechanism of your brain and that probably helps it stay in your memory longer and deeper. I am not an expert on this, but anyway, if you practice language more, you probably tend to remember it more.

-What should you shadow? My instinct would be to shadow "advanced speaking" such as a native speaker or high non-native speaker, but Wiltshier seems to prefer (at least for in-class activities) "peer shadowing," which asks one student to talk about a topic, and the other student shadow it. It is a good "active listening" activity for sure and requires to the speaker to speak clearly with the audience in mind. However, in my mind, active listening is active listening, and shadowing should be shadowing. Why would you intentionally "shadow" or imitate inaccurate, disfluent output of a peer? Hmm...I would still call that "active listening" and tell my students it is a good conversation strategy to show a speaker that you are following the person--it is definitely better than listening in a conversation with too much silence.

Wiltshier lists seven types of shadowing:

1. Full shadowing, where the speaker keeps speaking and the shadower keeps repeating everything with voice.
2. Slash shadowing, where / the speaker / deliberately / helps / the shadower / by pausing between phrases.
3. Silent shadowing, shadowing mentally only with no voice
   
4. Part shadowing, saying only key words
5. Part shadowing + comment. ....your dog, uh huh, hospital? I see. I'm sorry to hear that.
   
6. Part shadowing + question ....your dog, uh huh, hospital? When?
7. About You shadowing "I went shopping and..." "Oh, you went shopping and..."
   

For my ICU students (in my lessons this week), I plan to recommend full or silent or partial shadowing of native speaker recordings, but tell them it is also good to do some repeating of key words during a live conversation too.