Affiliations: Language and Brain Lab, School of Education, Tel Aviv
University, Tel Aviv, Israel
Note: [] Corresponding author: Naama Friedmann, Language and Brain Lab,
School of Education, Tel Aviv University, Tel Aviv 69978, Israel. Tel.: +972 3
6405257; Fax (in the UK): +44 870 1354671; E-mail: naamafr@post.tau.ac.il
Abstract: This study reports the reading of 11 Arabic-speaking individuals
with letter position dyslexia (LPD), and the effect of letter form on their
reading errors. LPD is a peripheral dyslexia caused by a selective deficit to
letter position encoding in the orthographic-visual analyzer, which results in
migration of letters within words, primarily of middle letters. The Arabic
orthography is especially interesting for the study of LPD because Arabic
letters have different forms in different positions in the word. As a result,
some letter position errors require letter form change. We compared the rate of
letter migrations that change letter form with migrations that do not change
letter form in 10 Arabic-speaking individuals with developmental LPD, and one
bilingual Arabic and Hebrew-speaking individual with acquired LPD. The results
indicated that the participants made 40% letter position errors in migratable
words when the resulting word included the letters in the same form, whereas
migrations that changed letter form almost never occurred. The error rate of
the Arabic-Hebrew bilingual reader was smaller in Arabic than in Hebrew.
However, when only words in which migrations do not change letter form were
counted, the rate was similar in Arabic and Hebrew. Hence, whereas
orthographies with multiple letter forms for each letter might seem more
difficult in some respects, these orthographies are in fact easier to read in
some forms of dyslexia. Thus, the diagnosis of LPD in Arabic should consider
the effect of letter forms on migration errors, and use only migratable words
that do not require letter-form change. The theoretical implications for the
reading model are that letter form (of the position-dependent type found in
Arabic) is part of the information encoded in the abstract letter identity, and
thus affects further word recognition processes, and that there might be a
pre-lexical graphemic buffer in which the checking of orthographic
well-formedness takes place.
Keywords: Dyslexia, letter position dyslexia, Arabic, abstract letter identity, developmental dyslexia
