If a person firmly believes in a non-factual statement, such as "The Earth is flat", and argues in its favor, there is no inherent intention to deceive. As the argumentation stems from genuine belief, it may be unlikely to exhibit the linguistic properties associated with deception or lying. This interplay of factuality, personal belief, and intent to deceive remains an understudied area. Disentangling the influence of these variables in argumentation is crucial to gain a better understanding of the linguistic properties attributed to each of them. To study the relation between deception and factuality, based on belief, we present the DeFaBel corpus, a crowd-sourced resource of belief-based deception. To create this corpus, we devise a study in which participants are instructed to write arguments supporting statements like "eating watermelon seeds can cause indigestion", regardless of its factual accuracy or their personal beliefs about the statement. In addition to the generation task, we ask them to disclose their belief about the statement. The collected instances are labelled as deceptive if the arguments are in contradiction to the participants' personal beliefs. Each instance in the corpus is thus annotated (or implicitly labelled) with personal beliefs of the author, factuality of the statement, and the intended deceptiveness. The DeFaBel corpus contains 1031 texts in German, out of which 643 are deceptive and 388 are non-deceptive. It is the first publicly available corpus for studying deception in German. In our analysis, we find that people are more confident in the persuasiveness of their arguments when the statement is aligned with their belief, but surprisingly less confident when they are generating arguments in favor of facts. The DeFaBel corpus can be obtained from https://www.ims.uni-stuttgart.de/data/defabel

翻译：如果一个人坚信“地球是平的”等非事实性陈述并为之辩护，其本质上并无欺骗意图。由于论证源于真实信念，这类文本可能难以呈现与欺骗或说谎相关的语言学特征。事实性、个人信念与欺骗意图之间的相互作用仍是研究不足的领域。厘清这些变量在论证中的影响，对于深入理解各自对应的语言学特征至关重要。为基于信念研究欺骗与事实性之间的关系，我们提出了DeFaBel语料库——一个基于信念欺骗的众包资源。构建该语料库时，我们设计了一项实验：要求参与者为“吃西瓜籽会导致消化不良”等陈述撰写论证，无论其事实准确性或参与者对该陈述的个人信念如何。除生成任务外，我们同时要求参与者披露对该陈述的个人信念。当所收集的实例与参与者个人信念相矛盾时，这些实例被标记为欺骗性。语料库中每个实例均标注（或隐含标记）作者的信念、陈述的事实性以及欺骗意图。DeFaBel语料库包含1031篇德语文本，其中643篇为欺骗性文本，388篇为非欺骗性文本，是首个公开的德语欺骗研究语料库。分析发现，当陈述与参与者信念一致时，参与者对自身论证的说服力更自信；但令人意外的是，当需为事实性陈述辩护时，其自信程度反而降低。DeFaBel语料库可通过https://www.ims.uni-stuttgart.de/data/defabel获取。