Children’s use of linguistic and non-linguistic negation in reasoning by the disjunctive syllogism

AbstractWhether logical inference is available without language is highly debated. One such inference is the disjunctive syllogism (A Or B, Not A, Therefore B). Evidence from a search task that required disjunctive reasoning suggests that that the syllogism is unavailable before age 3 (Mody & Carey, 2016). However, in a replication of the same task using language (i.e., verbal negation), even 2.5-year-olds succeeded (Grigoroglou, et al., 2019). Here we explore the role of language in children’s logical reasoning. 2.5- to 4-year-olds performed the non-linguistic task, after a short training in reasoning by exclusion. Half of the children received linguistic training (e.g., heard “there is no coin in X cup”); half received non-linguistic training (i.e., saw that one location was empty). Results show that 2.5- and 3-year-olds were more successful in reasoning with the disjunctive syllogism after the linguistic training. Thus, offering children the premise “Not A” verbally facilitated logical reasoning.

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