Text simplification refers to the process of increasing the comprehensibility of texts. Automatic text simplification models are most commonly evaluated by experts or crowdworkers instead of the primary target groups of simplified texts, such as persons with intellectual disabilities. We conducted an evaluation study of text comprehensibility including participants with and without intellectual disabilities reading unsimplified, automatically and manually simplified German texts on a tablet computer. We explored four different approaches to measuring comprehensibility: multiple-choice comprehension questions, perceived difficulty ratings, response time, and reading speed. The results revealed significant variations in these measurements, depending on the reader group and whether the text had undergone automatic or manual simplification. For the target group of persons with intellectual disabilities, comprehension questions emerged as the most reliable measure, while analyzing reading speed provided valuable insights into participants' reading behavior.

翻译：文本简化是指提升文本可理解性的过程。自动文本简化模型通常由专家或众包工作者评估，而非简化文本的主要目标群体（如智力障碍者）。我们开展了一项文本可理解性评估研究，参与对象包括智力障碍者和非智力障碍者，他们在平板电脑上阅读未简化、自动简化和手动简化的德语文本。我们探索了四种不同的可理解性测量方法：多项选择理解题、感知难度评分、响应时间和阅读速度。结果揭示了这些测量指标因读者群体和文本是否经过自动或手动简化而存在显著差异。对于智力障碍者这一目标群体，理解题是最可靠的测量方法，而分析阅读速度则能提供关于参与者阅读行为的宝贵见解。