Graduation Date

Fall 2023

Document Type



Master of Arts degree with a major in Psychology, option Academic Research

Committee Chair Name

Mari Sanchez

Committee Chair Affiliation

HSU Faculty or Staff

Second Committee Member Name

Brandilynn Villarreal

Second Committee Member Affiliation

HSU Faculty or Staff

Third Committee Member Name

Christopher Walmsley

Third Committee Member Affiliation

HSU Faculty or Staff

Subject Categories



This research used the BEST dataset gathered in 2017 by de Bruin and colleagues, which contains information gathered from 650 multilingual participants (435 female, Mage = 25.02) from the Basque Country at the Basque Center on Cognition, Brain and Language (BCBL). Multilingual individuals may have different levels of proficiency in each language they speak, and there are various factors that can influence proficiency. Such factors include the age at which they begin learning a language and how much exposure they have to the language. Proficiency can be assessed both subjectively (personal perception of proficiency) and objectively (observed and/or measured performance on proficiency tests). While most research on these topics have focused on bilingualism and relied heavily on subjective measures of proficiency, this study expands the literature by investigating the role of age of acquisition and exposure on multilingualism using both subjective and objective measures of proficiency. This thesis demonstrated the importance of taking into consideration factors beyond age of acquisition that may impact language proficiency, such as exposure, and supported the need to use a wide range of objective tests when measuring language proficiency.

Citation Style