The present study conducted a systematic review of the item response theory (IRT) literature in language assessment to investigate the conceptualization and operationalization of the dimensionality of language ability. Sixty-two IRT-based studies published between 1985 and 2020 in language assessment and educational measurement journals were first classified into two categories based on a unidimensional and multidimensional research framework, and then reviewed to examine language dimensionality from technical and substantive perspectives. It was found that 12 quantitative techniques were adopted to assess language dimensionality. Exploratory factor analysis was the primary method of dimensionality analysis in papers that had applied unidimensional IRT models, whereas the comparison modeling approach was dominant in the multidimensional framework. In addition, there was converging evidence within the two streams of research supporting the role of a number of factors such as testlets, language skills, subskills, and linguistic elements as sources of multidimensionality, while mixed findings were reported for the role of item formats across research streams. The assessment of reading, listening, speaking, and writing skills was grounded within both unidimensional and multidimensional framework. By contrast, vocabulary and grammar knowledge was mainly conceptualized as unidimensional. Directions for continued inquiry and application of IRT in language assessment are provided.

本研究对语言评估中的项目反应理论（IRT）文献进行了系统的综述，以研究语言能力维度的概念化和可操作性。1985年至2020年之间在语言评估和教育评估期刊上发表的62篇基于IRT的研究首先基于一维和多维研究框架分为两类，然后从技术和实质性角度进行审查以检查语言的维度。结果发现，采用了12种定量技术来评估语言维度。探索性因素分析是应用一维IRT模型的论文中进行维数分析的主要方法，而比较建模方法在多维框架中占主导地位。此外，在这两个研究流中，有越来越多的证据支持多种因素的作用，例如睾丸，语言技能，亚技能和语言因素作为多维来源，而对于各项目格式在整个过程中的作用，则报告了混合发现。研究流。阅读，听力，口语和写作技能的评估基于一维和多维框架。相反，词汇和语法知识主要被概念化为一维的。提供了在语言评估中继续查询和应用IRT的指示。和语言元素是多维的来源，而据报导，在研究流中，项目格式的作用存在混杂的发现。阅读，听力，口语和写作技能的评估基于一维和多维框架。相反，词汇和语法知识主要被概念化为一维的。提供了在语言评估中继续查询和应用IRT的指示。和语言元素是多维的来源，而据报导，在研究流中，项目格式的作用存在混杂的发现。阅读，听力，口语和写作技能的评估基于一维和多维框架。相反，词汇和语法知识主要被概念化为一维的。提供了在语言评估中继续查询和应用IRT的指示。