Lexical knowledge varies by modality, grammatical class, and, in Arabic diglossia, by the lexical distance between Modern Standard Arabic (MSA) and Spoken Arabic (SpA). We tested the effects of modality, grammatical class, and MSA–SpA distance on lexical knowledge, and interdependence between SpA and MSA. Palestinian Arabic (PA) speaking kindergarteners (N=30; mean age 5:9) completed picture naming tasks manipulating modality (comprehension and production), grammatical class (nouns and verbs), and lexical distance (identical, cognate, and unique). Scores were higher for nouns than verbs and for comprehension than production in both varieties. A graded distance effect was found (identical > cognate >unique). PA lexical knowledge predicted MSA lexical knowledge across conditions in production. These findings highlight the importance of the spoken variety in acquiring MSA vocabulary and show that linguistic distance constrains lexical acquisition in Arabic diglossia. We argue that models of vocabulary acquisition should incorporate linguistic distance and interdependence between varieties.
