We evaluated whether the processing of two-digit numbers was determined by the direction of reading in the two languages of bilingual individuals.

A group of Arabic (L1)/Spanish (L2) proficient bilinguals performed a comparison task with Arabic digits, Arabic number words and Spanish number words while the unit–decade compatibility effect was evaluated.

Participants showed a regular compatibility effect with Arabic digits. However, no compatibility effect was observed when they performed the task with verbal numbers, regardless of whether numbers were presented in Arabic or in Spanish.

The similar pattern of results across the bilinguals’ two languages suggests that the direction of the reading (right-to-left in Arabic and left-to-right in Spanish) did not influence the processing of verbal numbers.

This is the first study in which the unit–decade compatibility effect has been explored with Arabic/Spanish bilinguals.

The main point to highlight from this study is that bilinguals are not influenced by the reading direction of their languages when they process two-digit verbal numbers.