Mody and Carey (2016) investigated children's capacity to reason by the disjunctive syllogism by hiding stickers within two pairs of cups (i.e., there is one sticker in cup A or B, and one in cup C or D) and then showing one cup to be empty. They found that children as young as 3 years of age chose the most likely cup (i.e., not A, therefore choose B; and disregard C and D) and suggested that these children were representing the dependent relationship between A and B by applying the logical operator “or”. However, it is possible that children succeeded using simpler strategies, such as avoiding the empty cup and choosing within the manipulated pair. We devised a new version of the task in which a sticker was visibly removed from one of the four cups so that 2.5- to 5-year-old children (N = 100) would fail if they relied on such strategies. We also included a conceptual replication of Mody and Carey's (2016) original condition. Our results replicated their findings and showed that even younger children, 2.5 years of age, could pass above chance levels. Yet, 2.5-, 3- and 4-year-olds failed the new condition. Only 5-year-old children performed above chance in both conditions and so provided compelling evidence of deductive reasoning from the premise “A or B", where “or” is exclusive. We propose that younger children may instead conceive of the relationship between A and B as inclusive “or” across both versions of the task.

Mody和Carey（2016）通过将贴纸隐藏在两对杯子中（例如，杯子A或B中有一个贴纸，杯子C或D中有一个贴纸），然后将一个杯子展示给儿童，通过分离三段论调查了儿童的推理能力。是空的。他们发现3岁以下的孩子选择了最有可能的杯子（即，不是A，因此选择B；而忽略了C和D），并建议这些孩子通过应用逻辑来表示A和B之间的依赖关系运算符“或”。但是，孩子可能会使用更简单的策略来成功，例如避免空杯子，并在操纵对中进行选择。我们设计了该任务的新版本，其中明显地从四个杯子之一中除去了贴纸，以便2.5至5岁的孩子（N = 100），如果他们依靠这样的策略将会失败。我们还包括对Mody和Carey（2016）原始状况的概念性复制。我们的结果重复了他们的发现，并表明，即使年龄在2.5岁以下的幼儿也可以超过机会水平。然而，2.5岁，3岁和4岁的孩子没有通过新的条件。在这两种情况下，只有5岁的孩子在两种情况下的表现都超过了偶然性，因此可以从前提“ A或B”（其中“或”是唯一的）提供演绎推理的令人信服的证据。我们建议年龄较小的孩子可以考虑设想A之间的关系和B在任务的两个版本中均包含为“或”。