In a comment on the question Is there a scientific evidence of class / teacher importance for adult learners? Gavenkoa makes the following claim:
There is evidence that certain teaching activities has negative impact on exam scores. One of such thing is correction of oral mistakes.
I find that hard to believe. It is one thing to say that something has no noticeable impact (see Effectiveness of reformulating incorrect sentences as feedback?), but it is a very different thing to say that such teacher interventions may have a negative effect.
Which studies have shown that correcting a learner's oral mistakes in class has a negative impact?