Effects of Orthographic Input and Inhibitory Control on Second-Language Speech Production

The present study extends previous research reporting that orthographic forms, such as the use of a single letter or two letters to indicate the same sound, affect sound duration in second-language (L2) production. Native-language (L1) Korean L2 English sequential bilinguals performed a delayed repetition task for word pairs containing the same consonant or vowel spelled with one or two letters. Korean provided an interesting case because (1) it has an alphabetic orthographic system but not a Roman alphabet and thus, there may be no interorthographic interference and (2) it has no phonemic length contrast for vowels, whereas there is some disagreement on the contrastiveness of the consonant length, which can lead to an asymmetry in the grapheme-to-phoneme correspondence between vowels and consonants. The results showed that Korean learners produced the same English vowel with a short duration when spelled with a single letter and with a long duration when spelled with double letters or digraphs composed of two different letters; this variation in duration did not appear when producing English consonants spelled with a single or two letters. This study further examined whether individual differences in inhibitory control influenced the magnitude of orthographic effects in the production of English vowels by Korean learners. Individual differences in inhibitory control were not strongly related to the influence of orthography on vowel production.