Assessing "implicit difficulty" in second language acquisition: a case study of the Kazakh auxiliary verb system

The acquisition of auxiliary verbs in Kazakh poses a significant challenge for native Chinese speakers. Traditional research has predominantly focused on the morphological complexity of these verbs as an "explicit difficulty", but there has been a lack of systematic explanation for the deeper cognitive and conceptual roots of the acquisition challenges. From the perspectives of second language acquisition theory and linguistic typology, this study proposes an "implicit difficulty" assessment framework, using the Kazakh auxiliary verb system as a case study to analyze the underlying causes of acquisition difficulties. The research adopts a method combining theoretical construction and illustrative analysis, targeting native Chinese speakers learning Kazakh at the zero-beginner and elementary levels. Data are drawn from a secondary analysis of error corpora and statistical results from existing empirical studies, as well as a systematic review of linguistic facts from authoritative linguistic literature. The study found that acquisition difficulties exist not only at the surface level of forms but are also rooted in three implicit dimensions: (1) high cognitive processing complexity, manifested as ambiguous formfunction mapping, low perceptual salience, and extended processing chains; (2) significant conceptualtypological conflict, arising from fundamental differences between Chinese and Kazakh in the grammaticalization of aspect and the packaging of concepts; (3) subtle negative transfer from the first language, including interference from "false friends" and analytical thinking patterns. The constructed three-dimensional framework systematically reveals these underlying obstacles. The findings suggest that instruction should shift from "error correction" to "cognitive construction" by strengthening conceptual comparisons between Chinese and Kazakh, optimizing input for formmeaning mapping, and deepening output-based tasks so as to effectively promote acquisition.