Why exact repetition may be exactly . . .wrong (in pronunciation teaching and elsewhere)

This study is potentially something of a game changer, at least conceptually. A little background. In KINETIK work we make extensive use of gesture synchronized speech. Extensive. Something we "learned" early on was that 

• In modeling the gestures and getting learners to move along with us it was apparently critical to at least some learners that you try to stay in the same "track" in the visual field every time you use it in instruction. 
• If you didn't, some students (possibly as much as 5%) would become disoriented, unable to synchronize their body movements with the model. Some even experienced some "motion sickness." 
•  In effect, the variability in the position in the visual field could be disconcerting and disruptive. 

Turns out, we may have been actually approaching the problem from the wrong direction, that is doing our best to be as consistent in the patterns of the gestures we use as possible  . .  . was actually counterproductive!  

New research by Manenti, et al, Variability in training unlocks generalization in visual perceptual learning through invariant representations, summarized by NeuroscienceNews.com, demonstrated that variability in the repeated application in the visual field/tract may actually enhance learning of the pattern, itself. It does that in part, apparently, by presenting the pattern in varying contexts, perhaps giving it potentially wider applicability. 

Excerpt from the (exceptional) study: 

• . . . four groups of subjects were trained to detect small differences in the orientation of a line pattern. The relevant task was to detect the clockwise or counterclockwise slope of the lines. For each of two groups, the number of lines was changed during the experiment. This was the irrelevant stimulus.
• The subjects were still able to recognize the differences in the orientation of the line pattern, even when the number of lines was changed. They were able to perform the task even when they were shown entirely new line patterns or a new position on the screen that had not appeared during training. Thus, the increase in variability did not cause the learning process to deteriorate, but rather to generalize and even improve learning performance.
•  “We found that varying the number of lines during training led to better generalization of the actual task performance,”

Undoubtedly, that the same principle applies to repetition of sounds or words in instruction--and even formulations of ideas and concepts as well. (There is substantial research on the contribution of paraphrase training in writing instruction, for example.) 

The insights from this study are certainly worth repeating!

Source: 

Manenti, G., Dizaji, A.,Schwiedrzik, C. 
“Variability in training unlocks generalization in visual perceptual learning through invariant representations” in BioRxiv doi: https://doi.org/10.1101/2022.08.26.505408