Abstract
The mastery of morphological structure and vocabulary acquisition are significantly associated. However, the association between the abilities of L2 learners to manipulate morphological elements and develop vocabulary size with native Arabic speakers needs to be assessed. This study assesses the impact of morphological knowledge on lexical acquisition and processing among English-speaking learners of Arabic. The study focused on gender (masculine/feminine) and the complete number system (singular/dual/plural) by native English speakers. The error rates and error patterns were analysed carefully to provide insight into the learner's interlanguage grammar through the experiment. The experimental study design was used. The study sample included 40 of L2 Arabic speakers from Arabic language courses at major universities in Northern Virginia and Maryland. These were native English speakers with no exposure to Arabic before their enrolment in the university. The sample was divided into three groups (Group I, individual in the second year of Arabic program, Group II, individual in 3rd or 4th year of the program, and Group III control group, five native speakers of Arabic). Different tasks were presented to the groups, where PsychoPy software was used for task presentation. Audacity Version 2.0 was audio-recorded, transcribed, and coded by the experimenter. The production and comprehension test revealed that morphological problems are prevalent at the advanced proficiency level. It showed the role of animacy for the morphological variability and higher agreement accuracy for human targets. It concluded that morphological variability in L2 Arabic remains a persistent problem even at advanced levels of proficiency, extending to comprehension.