detecting errors

When proof-reading it can sometimes be an advantage to be a non-native speaker of the language in which the document in question is written. In our own language, we are often too dazzled by our familiar expectations to notice occasions on which they are not fulfilled. Faced, for example, with They want to to arrange payment we too readily normalize the text and perceive just the correct They want to arrange payment. But a NNS is more likely to be brought up short by the puzzling grammar of repeated to, and hence to detect the error.
Furthermore, it is typically NSs, not NNSs, who get confused about spelling problems such as there – their – they’re, your – you’re and its – it’s. As NSs we know what a word should sound like but may be uncertain how to represent it in writing. NNSs, on the other hand, are likely to be very aware of translation correspondences between the L2 and their native L1, where the English confusables are quite distinct.
I think I have already previously expressed my thanks to Masaki Taniguchi for repeatedly detecting various minor careless errors that I have committed in my blog postings over the years — typically, elementary typos or repeated words (often from when I have changed my mind about the best wording and end up with fragments of two different versions). As a NNS he can look at my effusions more objectively than I can myself.
These thoughts were prompted by a job I was doing yesterday. I was checking the draft of a document in Welsh, written by a Welsh native speaker. I am of course not a NS of Welsh, but learnt the language as an adult, by self-study and in evening classes in London.
The long and the short of it is that yesterday I was able to detect a fair number of errors of grammar and spelling that the author had overlooked in his own composition.
From my days in the classroom when I was learning Welsh I can remember one misguided teacher who chose to drill us learners on the distinction (in writing) between yw ‘is’ and i’w ‘to his’. This may be a tricky point for native speakers of southern Welsh, for whom the two expressions are homophonous. But it was not a problem for us NNSs: it would have never occurred to us to confuse them, since their translation equivalents are quite distinct. On the contrary, for some of us it might have come as a revelation to be told that the two are pronounced identically and could be confused by less-than-fully-literate NSs.
This is a special case of the more general principle that we can see other people’s mistakes more easily than our own. Get someone else to proof-read anything you write for publication. Ideally, perhaps, get two people to do it: one a NS and one a NNS.