Peculiarity in the pronunciation of phonological idioms

Question

In a thesis on multi-word units in dictionaries (page 16; pdf page 38), the researcher touches upon phonological idioms, using the definition:

a fixed expression which has an oddity of pronunciation

Then he mentions the following examples, noting that the oddity is in the capitalized predicates:

the penny DROPPED

the mind BOGGLES

the plot THICKENS

where the shoe PINCHES

I don’t really get the oddity in those pronunciations. Could you please further explain the idea?

I have done some research on Google, but all I found was that phonological idioms are in fact mostly common among children since they tend to mispronounce the words.

Answer 1

The paper actually explains what the oddity is: the capitalised words contain "the nuclear accent", which in English is "the last pitch accent in a prosodic phrase." (Wikipedia)

These examples, where the syllable carrying the nuclear accent is capitalised, are: the penny DROPPED 'the remark was understood', the mind BOGGLES 'I can't comprehend that', the plot THICKENS 'the affair becomes more confused' and where the shoe PINCHES 'where the difficulty is situated'.

— ALNASER, MOHAMMAD (2010) Multi-word Items in Dictionaries from a Translator's Perspective. Doctoral thesis, Durham University

That is, those phrases are always said with the accent on that word, even where (say) the plot is obvious and one might expect that word to bear the accent. In "the plot thickens" — and the other expressions — it never does; the capitalised words are always accented.

Indeed, when the noun is accented, it only serves to emphasise the idiom: "Well, the plot's thickened, even though the fog has cleared."