Two-year-olds' recognition of hierarchies - Evidence from their interpretation of the semantic relation between object labels

The present studies investigated 2-year-olds' recognition of hierarchies by examining under various conditions the relative frequency with which child ren interpreted novel and familiar labels for objects as mutually exclusive . Two-year-olds were taught novel labels in one of three ways: (a) inclusiv e input: "[novel label] is a kind of [familiar label]"; (b) exclusive input : "[novel label] is not a [familiar label]"; or (c) (Study 2) no relational input. The referents of the novel and familiar labels were taxonomically e ither: (a) strongly related (e.g., a fighter airplane and a passenger airpl ane), or (b) weakly related (e.g., a paint brush and a toothbrush). Childre n were less likely to interpret the labels as picking out mutually exclusiv e categories when: (a) the labels were introduced with the inclusive input; and (b) the referents of the labels were taxonomically strongly related. T his modulation of mutual exclusivity interpretations in response to the var ious hierarchical relations instantiated in the stimuli and input provides evidence for 2-yearolds' emerging capacity to recognize hierarchical relati ons. (C) 2001 Elsevier Science Inc. All rights reserved.