This study focuses on complexity matching and lexical matching to investigate speech convergence in the conversations of bilingual Persian-English speakers in three language conditions namely Persian, English, and mixed in the context of lingua receptiva as an attempt to investigate such matching mechanisms between a Latin-based language and a non-Latin-based language. Complexity matching investigates convergence in terms of the hierarchical temporal structure of human speech while lexical matching explores convergence in terms of the frequency occurrence of the matched lemmas. For this purpose, 14 master’s students from the Shahid Chamran University of Ahvaz majoring in English language conversed with one another in dyadic groups in three language conditions each of which had its own topic namely movies, music, and books. In complexity matching, Allan Factor analysis in terms of multiscale clustering of onset events was considered. In lexical matching, the focus was on the distribution of all lemmas and matched lemmas and the possible correlation between the two. The results revealed a gradual increase in Allan Factor log-log plots in relation to the longer timescales that correspond with discourse patterns for complexity matching. For lexical matching, the positive correlation between all lemmas and matched lemmas (r<sub>s = .607) suggested that as participants talked to each other more, they unconsciously tried to match their psychological perceptions with each other more. This suggests that speech convergence is vigorous in both bilingual and monolingual interactions.
