From the study:
"For the VR condition (verbal recast w/o gesture), the researcher provided recast only verbally, putting her hands down next to the side of her body to avoid gesturing."
Now, does that (standing motionless w/hands at sides) sound like anything close to natural teacher behavior/gesture? Really? I have got to see a video of that! In fact, I’d really have to see a video of everything that went on, to make sense of the study.
"In addition, the researcher tried not to stress any part of the recast in either condition to keep consistency."
Wow. How could you provide anything close to effective, meaningful feedback without stressing the part of the defective sentence or phrase that is being corrected?
"In all the instances, learners had the opportunity to modify their output; however, production of modified output was not enforced in the present study, to keep the flow of interaction and the saliency of feedback as equal as possible across conditions."
Not requiring at least some minimal "embodied" verbal response to such a gesture seems about as disembodying as you can get! Apparently, it was.
The research on the use of simple recasts, as Nakatsukasa points out, is pretty clear that they are, for the most part, not worth wasting your time on. So, "pointing out" a basically ineffectual recast with a disembodied gesture is supposed to make it more effective? It didn't. Surprise.
This is an important study, however, in that it represents quite accurately, I think, the way in which many researchers and practitioners view the place of gesture in language teaching, or even human communication for that matter: "add ons" that can be understood out of context and disembodied (not demanding a corresponding physical response in the body and mind of the other--the learner, as if gesture can be understood independent of the meaningful interaction in which it occurs.)
Something of a “How not to” guide of sorts.
What then is the "right" embodied and contextualized way to use gesture in teaching? Thought you were never going to ask! See Part 2, The right (haptic) way to use gesture in (at least) pronunciation teaching. Forthcoming, shortly!
Nakatsukasa, K. (2019). Gesture-enhanced recasts have limited effects: A case of the regular past tense, Language Teaching Research (11)1-29.