The Monitor Hypothesis is part of Stephen Krashen’s theory of Second Language Acquisition. The hypothesis is that the ‘monitor’ acts to apply conscious, explicit, learned grammar to ‘edit’ your output. The Monitor only does so when (a) you have enough time, (b) you focus on form/correctness, (c) you know a(n explicit rule) to apply. (you could know an implicit rule and apply it to, to be fair)
In Gaelic there is a structure called ‘the inverted nominal’. When your sentence begins with some kind of modal or modal-like construction, e.g. “I want, I need, I like, I dislike” etc.., then a direct object of the verb will precede it (the verb in question takes a form called the verbal noun).
Tha mi ag iarraidh cèic ithe – I want cake-to-eat.
Feumaidh tu bainne òl – You’ll need to drink milk.
I’m very familiar with the grammar rules that govern inverted nominals, I could explain them to you over and over. But when I’m speaking ex tempore and at pace, I often get them wrong. It doesn’t help that there are other verbal noun constructions that don’t invert. I suspect that in terms of order-of-acquisition, this one takes a while.
But this, of course, does not and has not stopped a teacher or two along my many-years Gaelic learning journey from both (a) explicitly correcting me, (b) marvelling, ‘How can you know this rule so well but you keep getting it wrong in speech? More practice needed!’
Now, I can tell you exactly why the second statement occurs. It’s not that I need more skill-practice, though it does help my monitor to do explicit skill practice. It’s that I need more and more comprehensible input. I need to hear those inverted nominal structures again, and again, and again, until they get deeply acquired, and not just explicitly learnt. ‘Cause I already learnt them, right? And any time you test me on them, with enough time, a focus on form, then I’ll apply the rules and get it ‘right’. But get my speaking at speed, and they’ll occasionally come out wrong.
As for dealing with teachers that like to error correct, even when you knew you said the wrong thing the moment it left your lips! (a not uncommon occurrence)? I’ve learnt to let it go. It depends on context, of course. In some circumstances, you could ask/tell a teacher/tutor to not correct you. In others, that ‘upward’ instruction/management might not be appropriate. Learning a language is relational, and this is one relationship you must navigate. So, as best you can, don’t take error correction to heart – it’s usually well meant, and if you can not get down about it, it probably won’t hurt you!