Sometimes the comments on this blog get sidetracked into topics that have nothing to do with the subject of the blog posting to which they are appended. So it was on 28 November, when David Marjanović was surprised “that anyone would seriously say anything other than [ˈt͡ʃɪkŋ̩]” for chicken.
As others sprang to point out, ˈtʃɪkɪn is in fact very common, indeed more than just common. It was the only form given in EPD when that dictionary was still edited by Jones, and indeed also under Gimson’s and then Ramsaran’s editorship. Only rather recently (since LPD came out, dare I venture?) have people started to recognize (for “BrE”, i.e. RP etc) the alternative possibility of ˈtʃɪkən, ˈtʃɪkn, ˈtʃɪkŋ. And I would guess that ˈtʃɪkɪn is still overwhelmingly the usual pronunciation for those who maintain the contrast of weak vowels in this position, ɪn vs. ən (the latter being also transformable into syllabic n and from there by progressive assimilation into syllabic ŋ).
For me the mystery is not so much the fact that the weak vowel in chicken is usually ɪ as the fact that the same is NOT true of thicken, stricken, quicken, sicken. They all have ə. I would guess that for most BrE speakers chicken ˈtʃɪkɪn does not rhyme with thicken ˈθɪkən, and I have no idea why that should be the case. Given the identical spelling and the similar morphology (a fairly transparent -en suffix), you would expect them to have the same vowels.
I can’t find anything relevant in Carney’s Survey of English Spelling (Routledge, 1994).
Here’s the OED.