This dataset contains the results from 100 native (L1) Dutch speakers from Flanders (Belgium). These participants completed a (i) lexical decision task and a (ii) phoneme categorisation task. In the lexical decision task, participants were exposed to the accented speech of one Italian L1 speaker of Dutch who pronounced 40 target words with either canonical productions of the /ɪ/-vowel but ambiguous realisations of the /i/-vowel (e.g., vlinder 'butterfly' as [ˈvlɪn.dər], but diefstal 'theft' as [ˈdi/ɪf.stɑl]), or vice versa. Participants’ comprehension of the target words was measured in terms ...