How might language affect critical thinking performance?

• We examined whether language structure or proficiency affect critical thinking.
• Japanese students show critical evaluation better in Japanese than in English.
• Proficiencies in native- and second-languages correlate with critical evaluation in writing.
• But without critical evaluation instruction, no such correlations were found.
• Results indicate importance of language proficiency and provision of instruction.

This study examined whether language structure or language proficiency might affect students’ critical thinking performance. Previous research has claimed that many non-Western students struggle with the demands of demonstrating critical thought. Two language-related causes have been suggested: one concerning structural limitations in the non-Western students’ first language, and the other concerning their second language proficiency. In Study 1 described here, reports written by 110 Japanese second year university students, who had received instruction in academic discourse for critical evaluation (which is one aspect of critical thinking), were analyzed for use of evaluative statements. No disadvantage was found for use of the Japanese language, which is considered as having a more indirect structure that may make critical evaluation more difficult. Measurements of language proficiency in English and Japanese, however, were found to correlate with production of evaluative statements in those respective languages suggesting that language proficiency could affect critical evaluation use. In Study 2, the same task was given to 43 first year students who had not yet received the same instruction. Analysis revealed similar patterns in their written work but at a lower level, suggesting that the second year students had benefitted from the skills instruction. Furthermore, unlike the second year students, the first year students evidenced no correlations between their language proficiency scores and their production of evaluative statements, suggesting that proficiency on its own is inadequate: students need instruction on the specific language forms and structures to use to demonstrate critical thinking in their written work.