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Poster A84, Tuesday, August 20, 2019, 10:15 am – 12:00 pm, Restaurant Hall

Effects and interactions of orthographic depth and lexicality in Arabic visual word recognition: A lexical decision ERP study

Ali Idrissi1, R. Muralikrishnan2, Eiman Mustafawi1, Tariq Khwaileh1, John Drury1;1Qatar University, 2Max Planck Institute for Empirical Aesthetics

INTRODUCTION. The Arabic script uses independent letters to represent consonants and long vowels, typically leaving short vowels unmarked. However, short vowels can be marked with diacritics, which provide studies of visual word recognition with degrees of deep/shallow orthography that can be examined in tightly matched minimal pairs. Using fMRI, Bourisly et al. (2013) show distinct activations suggestive of additional lexical search when diacritics are absent, and greater involvement of mappings to phonology/semantics when they are present (cf. Weiss et al. 2015). An Arabic semantic priming ERP study (Mountaj et al. 2015) found larger early negativities when diacritics were present (~N1 peak) but, surprisingly, no influence on N400 semantic relatedness effects (cf. Bar-Kochav & Breznitz 2012). PRESENT STUDY & METHODS. Here we employed a 2x3 design crossing LEXICALITY (real-/pseudo-words) with three levels of DIACRITIC DENSITY (fully-marked/(FULL), minimally-marked/(MIN), non-marked/(NON)). In minimally-marked cases a single diacritic was included where it could ensure disambiguation. Additionally, violations were tested with diacritics either indicating attested word patterns that do not occur with the given real-roots, or unattested patterns attached to either real- or pseudo-roots. Adult Qatari Arabic native speakers (n=33; all female) judged 720 items (half real-words) for LEXICALITY while EEG was continuously recorded. ERPs were examined in three sets of time-windows probing early evoked responses, the N400, and late positivities. Peak and (50% fractional peak) latencies were examined to probe N400 onset and offset timing. Lexical decision response latency/accuracy was also examined. Here we focus on early evoked potentials and on the N400. RESULTS. First, around the N1 peak ERP amplitudes varied parametrically with DIACRITIC DENSITY but in the opposite direction of previous studies (negativities largest for NON>MIN>FULL). Second, DIACRITIC x LEXICALITY interactions emerged in the form of earlier N400 onset for NON than FULL cases for real-words only, while the opposite pattern held for N400 offset, which was later for NON than FULL for pseudo-words only. Also, diacritics indicating unattested word patterns yielded the largest early negativity of any condition. This violation response was followed by a sustained negativity for real-words only. Real-word mismatches indicating possible word patterns did not show this large early negativity, though the subsequent sustained effect emerged later (~N400 peak). DISCUSSION. We suggest our opposite direction early effects are due to our relatively smaller proportion of NONmarked cases and the presence of diacritic violations/mismatches. However, this finding, coupled with the robust violation response for unattested diacritic patterns, clearly shows these initial stages of processing are sensitive to more than just mere visual load/complexity (contra previous studies). Further, our possible/attested diacritic mismatch cases provide information about the timing of root and word-pattern integration, which we discuss relative to findings from previous masking priming studies of Arabic (e.g., Boudelaa & Marslen-Wilson 2005). Finally, the N400 latency effects offer the promise that manipulations of diacritics could aid in adjudicating disputes about the etiology of this ERP component in addition to providing hitherto lacking evidence for the effect of orthographic depth on access/retrieval of semantic LTM during lexical decision.

Themes: Reading, Writing and Spelling
Method: Electrophysiology (MEG/EEG/ECOG)

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