Multilingualism has established itself as a separate area of research in linguistic studies for the two last decades. Therefore, the present study aims at examining Algerian Multilingual students' perceptions of linguistic distance i.e., "psychotypology," between their first Language Arabic and Second language French and third language English. It focuses on the role of psychotypology as a constraining factor of cross-linguistic influence in third language acquisition that may lead to the activation of the background languages in the production of L3 English. Therefore, the researcher used a mixed research method to explore which typological or psychotypological languages L1 Arabic or L2 French would be the source of language transfer in L3 production. Forty students participated in this study, and data was gathered through a psychotypological questionnaire. The results of a qualitative and quantitative analysis showed students perceive French as a closed language to English in most the language aspects and they used it to fill a linguistic gap in their English production. It also showed that psychotypology is a complex concept that would affect students' language choice in L3 production as well as a crucial factor in determining the source language of transfer. The findings indicated that further investigations of Psychotypology in L3 production are necessary.