If the LXX and thus the Hebrew background of the Greek verb + cognate participle are taken into account, any interpretation must see this construction as intensive; any translation must attempt to bring this out.
A survey of the English translations of Mk 4.12 will be illustrative at this point. Unfortunately, the AV translators apparently did not understand the idiom and rendered the text very literally: 'seeing they may see and not perceive; and hearing they may hear and not understand'.
Subsequent translations have followed suit:NASB: 'while seeing they may see and not perceive; and while hearing, they may hear and not understand' (similarly ASV, NKJV).
Others have attempted to do something beyond such a literal translation:JB: 'they may see and see again, but not perceive; may hear and hear again but not understand';
NEB: 'they may look and look, but see nothing, they may hear and hear and understand nothing'.
A few have apparently understood the intensive nature of this construction and tried to bring this out in translation:NIV: 'they may be ever seeing but never perceiving, and ever hearing but never understanding';
NAB: 'they will look intently and not see, listen carefully and not understand';
NRSV: 'they may indeed look, but not perceive, and may indeed listen, but not understand' (similarly RSV)
The translator should recognize the intensity of this construction and render it appropriately. The English method for intensifying a verb is frequently to use an adverb. The choice of adverb should be guided by the recognition that the Hebrew verb + cognate infinitive absolute construction seeks to intensify the verb's assertion, not its root meaning. Words like 'surely', 'certainly' (or 'most certainly') and 'intently' are appropriate. A possible translation of Mk 4.12 might be:They are sure to look and not really see,
They are sure to listen and not really understand.
A possible translation of Mt. 13.14 might be:You will surely listen but certainly not understand,
You will surely look but certainly not see.
— Mark Krause, in Biblical Greek Language and Linguistics, p.198-199