Orthographic forms affect speech perception in a second language: Consonant and vowel length in L2 English

Italian(L1) speakers of English(L2) produce the same English sound as longer if spelled with two than with one letter, following Italian grapheme-phoneme conversion rules. Do Italian listeners perceive short and long sounds in English homophonic word pairs that are spelled with a single letter or a digraph (finish-Finnish; morning-mourning)? In Experiment 1, 50 Italian(L1)-English(L2) bilinguals and 50 English controls performed a Consonant Perception task and a Vowel Perception Task. They heard English homophonic word pairs containing a target sound spelled with one or two letters and indicated whether the two words contained the same sounds or not. For half of the listeners a picture was used to activate target words (Auditory-Visual Input group). Bilinguals in this group perceived different sounds in homophonic pairs. Experiment 2 tested whether naturalistic exposure reduces orthographic effects on speech perception by comparing learners, sequential bilinguals, and English controls (all n = 30) with Auditory-Visual Input. Orthographic form (spelling) affected consonant perception in both of the second language listener groups. Learners were less affected than bilinguals. Analyses indicated that this was because of the learners' high proficiency. It appears that Italian(L1) speakers of English(L2) make a long-short contrast for consonants-unattested in English-and illusorily perceive it in spoken English homophonous words.Public Significance Statement The findings strongly suggest that spelling affects speech perception in a second language. Italian native speakers listened to pairs of English homophonic words (having the same sound) where a sound was spelled with one letter in one word and two letters in the other. The number of letters (one or two) in English spelling leads second language listeners to perceive an illusory contrast between short and long sounds in spoken English that does not exist in the English language. The findings highlight the importance of orthographic input in establishing mental representations of the phonological form (sound) of second language words. Findings also indicate that large amounts of naturalistic exposure do not reduce the effects of orthographic forms on second language speakers' speech perception.